# env.dev > Developer hub for AI-powered workflows, tools, and guides. Free client-side developer tools, in-depth guides, cheatsheets, and AI resource comparisons — no signup required. env.dev provides 42+ developer tools (JSON formatter, Base64 encoder, JWT debugger, regex tester, and more), all running client-side in the browser. It also offers comprehensive guides on topics like Docker Compose, .env files, cron expressions, JWTs, and AI-driven development patterns. ## Guides - [Dev Container Environment Variables](https://env.dev/guides/devcontainer-env-variables): Set Dev Container variables with containerEnv, remoteEnv, localEnv, and Docker Compose without confusing process scope or precedence. - [Cloudflare Workers Environment Variables](https://env.dev/guides/cloudflare-workers-env-variables): Configure Workers bindings, secrets, Wrangler environments, local .dev.vars precedence, and Node process.env behavior. - [uv Environment Variables and .env Files](https://env.dev/guides/uv-env-variables): Load .env files with uv run, apply later-file and shell precedence, disable loading, and separate app variables from uv configuration. - [Local LLMs for Coding in 2026: Models, Hardware, Runtimes](https://env.dev/guides/local-llms-for-coding): Local LLMs for coding in 2026: Qwen2.5-Coder 32B at 73.7 Aider, Ollama vs llama.cpp vs LM Studio, and how to point Cursor or Continue at localhost. - [Securing Your Dev Environment for AI Coding Agents](https://env.dev/guides/securing-dev-environment-ai-agents): Treat your AI coding agent as an untrusted intern: scope and expire API keys, lock down Docker egress, and assume prompt injection will exfiltrate secrets. - [jq: Filter and Transform JSON From the Command Line](https://env.dev/guides/jq): jq is the C-based JSON processor (1.8.1, 2025) that filters, reshapes, and pipes JSON inside shell scripts. Recipes for kubectl, GitHub API, and AWS CLI. - [tmux: Sessions, Panes, .tmux.conf, and Neovim Integration](https://env.dev/guides/tmux): tmux is the BSD-licensed terminal multiplexer (3.6a, 2026) that survives SSH drops and reboots. Sessions, panes, .tmux.conf, scripting, and Neovim. - [Docker on Windows 2026: Desktop, WSL2, Rancher, Podman](https://env.dev/guides/docker-on-windows): Docker on Windows runs four ways in 2026: Docker Desktop, Docker Engine in WSL2, Rancher Desktop, or Podman Desktop. Licensing, performance, and how to pick. - [How to Build an MCP Server: TypeScript & Python (2026)](https://env.dev/guides/how-to-build-an-mcp-server): Build a Model Context Protocol server in TypeScript or Python in 2026: SDK quickstart, transports (stdio vs Streamable HTTP), security, and client setup. - [MCP Server Environment Variables & Secrets](https://env.dev/guides/mcp-server-env-variables): How MCP servers receive secrets through the env block, why stdio servers do not inherit your shell, and scoping tokens so prompt injection cannot drain them. - [OpenGraph Image Not Showing: 8 Causes and Fixes](https://env.dev/guides/opengraph-image-not-showing): Why your og:image is not rendering on Facebook, LinkedIn, Slack, or Discord — caching, absolute URLs, size limits, hotlink protection, and robots.txt blocks. - [OpenGraph Image Sizes 2026: Per-Platform Cheat Sheet](https://env.dev/guides/opengraph-image-sizes): Recommended OpenGraph image sizes per platform in 2026: universal safe size, aspect ratios, file size limits, and how each platform crops on mobile. - [Vite Environment Variables: import.meta.env & Modes](https://env.dev/guides/vite-env-variables): Vite exposes only VITE_-prefixed vars on import.meta.env, statically replaced at build time. Covers .env modes, loadEnv, define, and undefined-var gotchas. - [Build-Time vs Runtime Environment Variables](https://env.dev/guides/build-time-env-variables): Build-time env vars are inlined into your bundle and frozen until you rebuild; runtime vars are read from process.env on each start. When to use each. - [Bun Environment Variables: Bun.env & .env Auto-Load](https://env.dev/guides/bun-env-variables): Bun auto-loads .env, .env.{NODE_ENV}, and .env.local with no dotenv install. Bun.env vs process.env, $VAR expansion, --env-file, and build inlining gotchas. - [Laravel Environment Variables: env(), config() & Caching](https://env.dev/guides/laravel-env-variables): env() returns null after php artisan config:cache — the #1 Laravel env trap. env() vs config(), APP_KEY rotation, .env precedence, and deployment caching. - [Django Environment Variables: settings.py Patterns](https://env.dev/guides/django-env-variables): Configure Django with os.environ and django-environ: DEBUG, SECRET_KEY, and DATABASE_URL in settings.py, .env files in dev, real env vars in production. - [Windows Environment Variables: setx, set & PowerShell](https://env.dev/guides/windows-environment-variables): set is session-only, setx persists but truncates at 1,024 chars, PowerShell has $env: and [Environment]. User vs system scope, PATH pitfalls, GUI editor. - [Next.js Environment Variables: Complete Guide](https://env.dev/guides/nextjs-env-variables): How Next.js handles environment variables: .env file load order, NEXT_PUBLIC_ prefix, server vs client access, and common production errors. - [GitHub Actions: Secrets vs Environment Variables](https://env.dev/guides/github-actions-secrets-env): When to use repository secrets, environment secrets, and configuration variables in GitHub Actions. Includes workflow examples for Node.js, Python, and Docker. - [Node.js Env Variables: process.env, dotenv & --env-file](https://env.dev/guides/nodejs-env-variables): How to use environment variables in Node.js: process.env, dotenv, the Node 20.6+ --env-file flag, NODE_ENV, type-safe validation with zod. - [Fix 'NODE_NO_WARNINGS is not recognized' on Windows](https://env.dev/guides/node-no-warnings-not-recognized): On Windows, NODE_NO_WARNINGS=1 node app.js fails: cmd parses the inline env var as a command. Fix with set, PowerShell $env:, cross-env, or --disable-warning. - [Gemini API Environment Variables: Keys & Vertex AI](https://env.dev/guides/gemini-api-env-variables): GEMINI_API_KEY and GOOGLE_API_KEY both auto-load in the google-genai SDK; GOOGLE_API_KEY wins if both set. Vertex AI needs project + location, not a key. - [Env Variables Security: Secrets, Leaks & Best Practices](https://env.dev/guides/env-vars-security): Why environment variables are not truly secure and what to do about it: secret rotation, leak detection, client-side risk, and secrets managers. - [Google Maps API Key Gemini Abuse: Stop Surprise Bills](https://env.dev/guides/google-maps-api-key-gemini-billing): A leaked Google Maps API key can now call paid Gemini APIs and run up huge bills. Lock keys down with API restrictions and budgets — and recover after abuse. - [Go Environment Variables: os.Getenv, godotenv & Viper](https://env.dev/guides/go-env-variables): How to read, set, and manage environment variables in Go. Covers os.Getenv, os.LookupEnv, godotenv, Viper, envconfig, build-time variables, and testing. - [JWT Best Practices: Storage, Algorithms & Revocation](https://env.dev/guides/jwt-best-practices): Security best practices for JSON Web Tokens: algorithm selection, storage, expiration, refresh patterns, revocation, and common vulnerabilities. - [Docker Env Variables: ENV, ARG & Runtime](https://env.dev/guides/docker-env-variables): How to use environment variables in Docker: ENV vs ARG in Dockerfile, docker run -e, --env-file, multi-stage builds, BuildKit secrets, and best practices. - [Vercel Environment Variables: Dashboard, CLI & Edge](https://env.dev/guides/vercel-env-variables): How to configure environment variables on Vercel: the dashboard, CLI (vercel env pull), system variables, per-env settings, and Edge function access. - [.env File Syntax Rules: Quoting, Comments, Multiline](https://env.dev/guides/env-file-syntax): Compare measured .env parsing in Node, npm dotenv, Python, Docker Compose, and Docker CLI: whitespace, comments, quotes, multiline values, and expansion. - [Kubernetes Env Variables: ConfigMaps, Secrets & Pod Spec](https://env.dev/guides/kubernetes-env-variables): How to configure environment variables in Kubernetes: inline env, ConfigMaps, Secrets, the downward API, and best practices for managing configuration at scale. - [AWS Lambda Env Vars: Console, CLI, SAM & CDK](https://env.dev/guides/aws-lambda-env-variables): How to set and manage environment variables in AWS Lambda: the console, CLI, SAM, CDK, Terraform, KMS encryption, and Secrets Manager. - [Python Env Variables: os.environ, dotenv & Pydantic](https://env.dev/guides/python-env-variables): How to read, set, and manage environment variables in Python. Covers os.environ, python-dotenv, Pydantic Settings v2, and Django/Flask configuration patterns. - [How to Share .env Files With Your Team Securely](https://env.dev/guides/sharing-env-files-securely): Share .env files securely with send.env.dev — end-to-end encrypted, burn-on-first-read links, EU-hosted, zero dependencies. Plus 1Password, Doppler, Vault. - [Terraform Variables: tfvars vs Env Vars vs Blocks](https://env.dev/guides/terraform-variables): The three ways to set Terraform variables: variable blocks, .tfvars files, TF_VAR_ env vars, precedence, sensitive values, and validation. - [OpenTofu in 2026: Open-Source Terraform Fork Explained](https://env.dev/guides/opentofu): OpenTofu 1.11 is the Linux Foundation fork of Terraform 1.5 under MPL 2.0, with built-in state encryption, ephemeral values, and a drop-in tofu CLI. - [Pulumi vs Terraform vs OpenTofu: Getting Started 2026](https://env.dev/guides/pulumi-getting-started): Pulumi 3.236 writes cloud infra in TypeScript, Python, Go, or C# under Apache 2.0. Compared with Terraform and OpenTofu, plus a first AWS S3 stack walkthrough. - [dotenv Not Loading? Step-by-Step Debugging Guide](https://env.dev/guides/dotenv-not-loading): Fix environment variables not loading from .env files. Covers Node.js, Python, Docker, file path issues, syntax errors, load order, and production gotchas. - [Next.js Env Variables Undefined: Causes & Fixes](https://env.dev/guides/next-env-variables-undefined): NEXT_PUBLIC_ vars undefined in the browser, server vars missing, or values frozen after deploy — every Next.js env variable failure mode and its fix. - [Vite Env Variable Undefined? import.meta.env Fixes](https://env.dev/guides/vite-env-variables-undefined): import.meta.env.VITE_X undefined? Usual causes: missing VITE_ prefix, process.env in the browser, stale dev server, dynamic key access, wrong .env path. - [React Env Variables Undefined: CRA & Vite Fix](https://env.dev/guides/react-env-variables-undefined): React env variables return undefined unless prefixed REACT_APP_ (CRA) or VITE_ (Vite) and the dev server is restarted. Values inline at build time, not secret. - [Docker env variables not working in containers](https://env.dev/guides/docker-env-variables-not-working): Docker env variables not working usually comes down to ARG vs ENV scope, exec-form CMD skipping the shell, or .env only feeding Compose interpolation. - [Neovim Lua: Env Variables, vim.api & init.lua](https://env.dev/guides/neovim-lua): Pass env vars to vim.fn.jobstart, learn the vim.* namespace (vim.fn, vim.api, vim.opt), and build a clean init.lua with autocommands and vim.uv async I/O. - [GraphQL: Developer Guide to Queries, Schemas & APIs](https://env.dev/guides/graphql-guide): Learn GraphQL from scratch: SDL schema design, queries, mutations, subscriptions, resolvers, the N+1 problem with DataLoader, pagination, and security. - [WebSockets: Guide to Real-Time Communication](https://env.dev/guides/websockets-guide): WebSockets end to end: the RFC 6455 protocol, handshake, browser API, server code in Node.js, Python, and Go, reconnection, heartbeats, and scaling. - [Server-Sent Events: SSE vs WebSockets Guide](https://env.dev/guides/server-sent-events): Server-Sent Events (SSE): wire format, EventSource API, a Node.js TypeScript implementation, auto-reconnection, HTTP/2 multiplexing, and SSE vs WebSockets. - [AI Dark Factory Part 5: Security & Governance](https://env.dev/guides/dark-factory-pattern-part-5): Secure an AI dark factory with harness engineering: defense in depth, OS sandboxing, secrets, supply-chain lockdown, audit trails, and the OWASP Agentic Top 10. - [GitHub Actions: The Complete CI/CD Guide for Developers](https://env.dev/guides/github-actions-guide): GitHub Actions CI/CD: workflow syntax, triggers, matrix builds, reusable workflows, composite actions, caching, secrets, and security hardening. - [Git for Beginners: Visual Guide to Version Control](https://env.dev/guides/git-getting-started): Learn Git from scratch: cloning, branching, committing, pushing, pull requests, and resolving conflicts, with VS Code and GitHub Desktop walkthroughs. - [pgvector: Using Postgres as a Vector Database](https://env.dev/guides/postgres-vector-database): pgvector adds vector similarity search to Postgres: HNSW indexes, working SQL for RAG, benchmark numbers vs Pinecone, and when a dedicated store wins. - [Postgres Full-Text Search vs Elasticsearch](https://env.dev/guides/postgres-full-text-search): tsvector and a GIN index cover most search needs without Elasticsearch. Working SQL, ranking, typo tolerance with pg_trgm, BM25 via ParadeDB, and limits. - [Postgres as a Message Queue with SKIP LOCKED](https://env.dev/guides/postgres-as-a-queue): FOR UPDATE SKIP LOCKED turns a Postgres table into a job queue with transactional enqueue. Working SQL, LISTEN/NOTIFY, pgmq, and when you still need Kafka. - [Just Use Postgres: One Database for Almost Everything](https://env.dev/guides/just-use-postgres): PostgreSQL covers caching, queues, search, vectors, and documents through extensions. Why one database beats five systems — and where the limits are. - [PostgreSQL vs MongoDB: Why Postgres Wins](https://env.dev/guides/postgresql-vs-mongodb): PostgreSQL vs MongoDB compared head-to-head: when to choose which, why Postgres wins for 95% of projects, JSONB vs documents, and free hosting tiers. - [CORS: The Complete Guide to Cross-Origin Resource Sharing](https://env.dev/guides/cors-guide): CORS in depth: headers, preflight and credentialed requests, debugging, third-party scripts (Google Ads, Cloudflare, PostHog), and framework setup. - [AI Dark Factory Part 4: Scaling Agentic Coding](https://env.dev/guides/dark-factory-pattern-part-4): Scale your AI dark factory: git worktrees, Agent Teams, model routing, prompt caching, budget gates, observability, and agentic coding economics that work. - [AI Dark Factory Part 3: Spec-Driven Development](https://env.dev/guides/dark-factory-pattern-part-3): Spec-driven agentic coding for an AI dark factory: write precise specs, run holdout scenarios as quality gates, build an eval pipeline, and auto-merge safely. - [Dev Containers: Guide to Containerized Development](https://env.dev/guides/dev-containers): Dev Containers from devcontainer.json to Features, lifecycle scripts, Docker Compose, the CLI, performance tuning, security, and the gotchas. - [AI Dark Factory Part 2: Agent Setup & AGENTS.md](https://env.dev/guides/dark-factory-pattern-part-2): Set up your AI dark factory agent: install Claude Code, write a production-grade AGENTS.md, decompose agentic coding tasks, and build feedback loops that learn. - [AI Dark Factory: Autonomous Coding Explained](https://env.dev/guides/ai-dark-factory): AI dark factory: autonomous coding where agents write, test, and ship without human review. Coined by Dan Shapiro, Glowforge, January 2026. - [AI Dark Factory Playbook: From Autocomplete to Autonomous](https://env.dev/guides/dark-factory-pattern): Six-level AI dark factory playbook from manual coding (Level 0) to fully autonomous code (Level 5). Concrete agentic-coding actions, real numbers, no hype. - [Neovim: A Developer Guide to the Modern Vim](https://env.dev/guides/neovim): Master Neovim: modes, motions, text objects, registers, built-in LSP, Tree-sitter, Lua configuration, lazy.nvim plugins, and macros. - [Docker Compose Environment Variables: The Complete Guide](https://env.dev/guides/docker-compose-env-variables): Use environment variables in Docker Compose: .env auto-load, env_file, --env-file, multi-environment patterns, substitution, and secrets. - [The .env File: A Complete Guide to Environment Variables](https://env.dev/guides/dotenv): Everything about .env files: syntax rules, parser quirks, language examples (Node, Python, Go, Docker), best practices, and the gotchas that bite. - [Cron Expression Syntax: A Complete Guide](https://env.dev/guides/cron-expression-guide): Cron expression syntax explained: 5- and 6-field formats, special characters (* , - / L W #), common schedules, and platform-specific differences. - [Unix Timestamps Explained](https://env.dev/guides/unix-timestamps-explained): What Unix epoch time is, why it is used, how the Y2K38 problem threatens 32-bit systems, and how to generate and convert timestamps across languages. - [Base64 Encoding Explained](https://env.dev/guides/base64-encoding-explained): Understand Base64 encoding end-to-end: how the algorithm maps bytes to 64 characters, when to use it, what padding means, and why it inflates size by 33%. - [What is a JWT? A Developer Guide to JSON Web Tokens](https://env.dev/guides/what-is-jwt): Learn how JSON Web Tokens work — header, payload, and signature structure, typical auth use cases, common pitfalls, and best practices for secure usage. - [TypeScript Generics: A Complete Guide](https://env.dev/guides/typescript-generics): Master TypeScript generics with practical examples — type parameters, constraints, utility types (Partial, Pick, Omit), mapped and conditional types. - [REST API Best Practices: Design Guide](https://env.dev/guides/rest-api-best-practices): REST API design conventions used by Stripe, GitHub, and Google: URI naming, versioning, cursor pagination, error envelopes, status codes, auth, and HATEOAS. - [SSH Keys: Complete Guide to Generation and Usage](https://env.dev/guides/ssh-keys-guide): Generate Ed25519 SSH keys, configure ssh-agent and ~/.ssh/config, set up tunnels and ProxyJump, and harden sshd_config for production servers. - [Docker Networking: Bridge, Host, Overlay & Compose](https://env.dev/guides/docker-networking): Docker networking deep dive: bridge, host, overlay, macvlan drivers, port mapping, embedded DNS at 127.0.0.11, Compose isolated networks, and debugging. - [Linux File Permissions: chmod, chown, umask & ACLs](https://env.dev/guides/linux-file-permissions): Linux file permissions reference: chmod octal/symbolic, chown, umask, SUID/SGID/sticky bits, POSIX ACLs (setfacl/getfacl), and Linux capabilities. - [Nginx Configuration: Server Blocks, Proxy & SSL](https://env.dev/guides/nginx-configuration): Production Nginx config: server blocks, reverse proxy, SSL/TLS termination with Let's Encrypt, upstream load balancing, proxy caching, and rate limiting. - [Git Branching Strategies: GitFlow, Trunk-Based & GitHub Flow](https://env.dev/guides/git-branching-strategies): Compare Git branching strategies: GitFlow, trunk-based development, GitHub Flow, and release branches. Choose the right workflow for your team. - [Python Virtual Environments: venv, uv, Poetry & pyenv](https://env.dev/guides/python-virtual-environments): Manage Python environments with venv, pip, pyenv, Poetry, and conda. Learn requirements.txt, pyproject.toml, and environment best practices. - [HTTPS and TLS Explained: Certificates, Handshake & HSTS](https://env.dev/guides/https-tls-explained): Understand HTTPS, TLS certificates, the TLS handshake, cipher suites, Let's Encrypt, and HSTS for secure web communication. - [DNS Explained: Record Types, Resolution & Common Issues](https://env.dev/guides/dns-explained): Understand DNS record types, resolution process, caching, TTL values, and how to debug common DNS misconfigurations. - [Open Graph Protocol: Complete Social Sharing Guide (2026)](https://env.dev/guides/opengraph): Open Graph meta tags in 2026: required fields, image sizes for Facebook/LinkedIn/X/Slack, Twitter Cards, dynamic OG images, debugging, and caching. - [Regex Patterns Cookbook: Common Patterns with Explanations](https://env.dev/guides/regex-patterns-cookbook): A cookbook of common regex patterns for email, URL, IP address, phone number, and date validation with detailed explanations. - [Rate Limiting: Token Bucket, Sliding Window & More](https://env.dev/guides/rate-limiting-strategies): Implement rate limiting with token bucket, sliding window, fixed window, and Redis-based strategies. Code examples, edge patterns, and API gateways. - [Environment Variables in Rust: std::env, dotenvy & envy](https://env.dev/guides/rust-env-variables): Read env vars in Rust with std::env::var, load .env files via dotenvy, and deserialize typed config with envy. Plus the Rust 2024 unsafe-set_var change. - [Environment Variables in Java: System.getenv & Spring Boot](https://env.dev/guides/java-env-variables): Read env vars in Java with System.getenv() (immutable inside the JVM), bind to typed config via Spring Boot relaxed binding, plus dotenv-java for non-Spring. - [Ruby Environment Variables: ENV, dotenv & Rails Credentials](https://env.dev/guides/ruby-env-variables): Read env vars in Ruby with ENV.fetch, load .env files with the dotenv gem (the original dotenv port), and choose dotenv-rails or Rails encrypted credentials. - [Environment Variables in PHP: getenv, $_ENV & phpdotenv](https://env.dev/guides/php-env-variables): Three ways PHP reads env vars (getenv, $_ENV, $_SERVER). Plus vlucas/phpdotenv, Laravel's env() vs config(), and the FPM thread-safety gotcha. - [C# / .NET Environment Variables & IConfiguration](https://env.dev/guides/csharp-env-variables): In C# / .NET, prefer IConfiguration over Environment.GetEnvironmentVariable, and map nested keys with double underscores (ConnectionStrings__Default). - [Environment Variable Best Practices (2026)](https://env.dev/guides/env-vars-best-practices): Manage env vars without leaking secrets: SCREAMING_SNAKE_CASE naming, .env in .gitignore from day one, startup validation, typed config objects, and rotation. - [Env Vars in Docker, CI/CD & Kubernetes](https://env.dev/guides/env-vars-tips): Tactical env-var patterns: --mount=type=secret beats ARG, GitHub/GitLab/Jenkins idioms, ConfigMaps vs Secrets in Kubernetes, and build-time vs runtime split. - [Constants in JavaScript & TypeScript: const & as const](https://env.dev/guides/javascript-constants): JS const blocks reassignment, not mutation. Real immutability needs Object.freeze (ES5) or TypeScript's as const assertion (TS 3.4, 2019) at zero runtime cost. - [Constants in Python: typing.Final, Enum & SCREAMING_SNAKE](https://env.dev/guides/python-constants): Python has no const keyword. Constants follow SCREAMING_SNAKE_CASE per PEP 8, typing.Final adds mypy enforcement, and enum or MappingProxyType lock closed sets. - [Constants in Go: const, iota & Type-Safe Enumerations](https://env.dev/guides/go-constants): Go const is compile-time only — no address, inlined at every use. Untyped constants adopt their use-site type; iota generates enum sequences and bitmasks. - [Constants in Rust: const, static, const fn & LazyLock](https://env.dev/guides/rust-constants): Rust splits constants: const inlines at every use site; static has a fixed address. const fn runs at build time; LazyLock (1.80) gives thread-safe global state. - [Constants in Java: static final, Enums & List.of](https://env.dev/guides/java-constants): Java constants are static final fields. Compile-time inlining breaks consumers when library values change. List.of/Map.of/Set.of (Java 9+) are truly immutable. - [Constants: Naming, Immutability & Magic Numbers](https://env.dev/guides/constants-best-practices): Rules for good constants: SCREAMING_SNAKE_CASE with unit suffixes, real immutability per language, one source of truth, no magic numbers. Per Effective Java. - [Constants Tips: Tree Shaking, Branded Types & Test Fixtures](https://env.dev/guides/constants-tips): Compile-time vs runtime constants, bundler tree-shaking and dead-code elimination, constant folding, TypeScript branded types, and derived config. ## Cheatsheets - [Docker Compose Cheat Sheet — CLI, Health Checks & Watch](https://env.dev/cheatsheets/docker-compose-cheat-sheet): Docker Compose commands, compose.yaml keys, depends_on health conditions, profiles, and develop.watch live reload — plus the gotchas that break stacks. - [sed & awk Cheat Sheet — Text Processing One-Liners](https://env.dev/cheatsheets/sed-awk-cheat-sheet): sed and awk one-liners for substitution, line ranges, field extraction, and aggregation — with the GNU vs BSD traps that break scripts on macOS. - [PowerShell Cheat Sheet — Cmdlets, Pipeline & Objects](https://env.dev/cheatsheets/powershell-cheat-sheet): PowerShell 7 cmdlets, the object pipeline, filtering, environment variables, and execution policy — plus what differs from Windows PowerShell 5.1. - [OpenGraph Meta Tags Cheat Sheet — Sizes, Tags, Twitter Cards](https://env.dev/cheatsheets/opengraph-cheat-sheet): Every OpenGraph and Twitter Card tag with recommended image sizes per platform (Facebook, LinkedIn, X, Slack, Discord) and a copyable HTML template. - [HTTP Status Codes — Complete Quick Reference](https://env.dev/cheatsheets/http-status-codes-cheat-sheet): Every HTTP status code explained with practical examples. 1xx through 5xx with when to use each code in your API. - [CIDR Notation Cheat Sheet — Subnet Masks & Host Counts](https://env.dev/cheatsheets/cidr-cheat-sheet): Complete CIDR reference table: every prefix from /8 to /32 with subnet mask, total addresses, usable hosts, and common use cases. - [YAML Syntax Cheat Sheet — Scalars, Collections & Gotchas](https://env.dev/cheatsheets/yaml-cheat-sheet): Quick reference for YAML syntax: strings, numbers, multiline values, sequences, mappings, anchors, aliases, and common gotchas like the Norway problem. - [JSON Cheat Sheet — Syntax, Parsing & Common Mistakes](https://env.dev/cheatsheets/json-cheat-sheet): Quick reference for JSON syntax: data types, objects, arrays, JSON.parse/stringify, jq basics, and common mistakes like trailing commas and single quotes. - [Cron Schedule Examples — 30+ Common Cron Expressions](https://env.dev/cheatsheets/cron-examples-cheat-sheet): Ready-to-use cron expressions for every common schedule: every 5 minutes, hourly, daily, weekly, monthly, and more. - [Nginx Cheat Sheet — Server Blocks, Proxy & SSL](https://env.dev/cheatsheets/nginx-cheat-sheet): Quick reference for Nginx: service management, server blocks, reverse proxy, load balancing, SSL/TLS, location matching, logging, and performance tuning. - [tmux Cheat Sheet — Sessions, Windows, Panes & Copy Mode](https://env.dev/cheatsheets/tmux-cheat-sheet): Quick reference for tmux: sessions, windows, panes, copy mode, resizing, synchronize panes, configuration, and keybindings. - [Bash Scripting Cheat Sheet](https://env.dev/cheatsheets/bash-scripting-cheat-sheet): Quick reference for Bash scripting: variables, parameter expansion, conditionals, loops, functions, arrays, redirection, error handling, and strict mode. - [curl Cheat Sheet — HTTP Requests & API Testing](https://env.dev/cheatsheets/curl-cheat-sheet): Quick reference for curl: GET/POST requests, headers, cookies, authentication, file uploads and downloads, debugging, TLS, proxies, and scripting patterns. - [jq Cheat Sheet — Filter & Transform JSON](https://env.dev/cheatsheets/jq-cheat-sheet): jq commands for filtering, transforming, and merging JSON: filters, pipes, select, map/reduce, path expressions, output formatting, plus jq 1.8 changes. - [GitHub Actions Cheat Sheet](https://env.dev/cheatsheets/github-actions-cheat-sheet): Quick reference for GitHub Actions CI/CD: workflow syntax, triggers, jobs, matrix strategies, secrets, caching, artifacts, and reusable workflows. - [PostgreSQL Cheat Sheet](https://env.dev/cheatsheets/postgresql-cheat-sheet): PostgreSQL reference: CRUD, JOINs with visual diagrams, subquery vs JOIN vs CTE, window functions, indexing, JSONB, transactions, and performance tuning. - [Terraform Cheat Sheet](https://env.dev/cheatsheets/terraform-cheat-sheet): Quick reference for Terraform CLI commands, HCL configuration syntax, state management, workspaces, expressions, and built-in functions. - [Kubernetes (kubectl) Cheat Sheet](https://env.dev/cheatsheets/kubernetes-cheat-sheet): Quick reference for kubectl: contexts, core resources, pod operations, deployments, scaling, debugging, ConfigMaps, and Secrets. - [SSH Cheat Sheet](https://env.dev/cheatsheets/ssh-cheat-sheet): Quick reference for SSH: connecting, key generation, agent, port forwarding, jump hosts, SCP, SFTP, config file, and permissions. - [Neovim Cheat Sheet](https://env.dev/cheatsheets/neovim-cheat-sheet): Essential Neovim commands and keybindings: modes, navigation, editing, text objects, search, windows, buffers, macros, and more. - [Regex Cheat Sheet for Developers](https://env.dev/cheatsheets/regex-cheat-sheet): Quick reference for regular expressions: character classes, quantifiers, anchors, lookaheads, and capture groups — with copy-paste examples for common matches. - [Git Cheat Sheet — Undo, Rebase & Resolve Conflicts](https://env.dev/cheatsheets/git-cheat-sheet): Essential Git commands: how to undo the last commit, resolve merge conflicts, rebase branches, squash commits, and one-liners you always forget. - [Docker Cheat Sheet](https://env.dev/cheatsheets/docker-cheat-sheet): Docker CLI quick reference — the commands you actually use: run, exec, build, compose up/down, volumes, networks, prune, images, and common debugging flags. - [Python Cheat Sheet — Quick Reference](https://env.dev/cheatsheets/python-cheat-sheet): Python quick reference: data types, string methods, list/dict comprehensions, f-strings, file I/O, and common standard library modules. - [JavaScript Cheat Sheet — ES6+ Quick Reference](https://env.dev/cheatsheets/javascript-cheat-sheet): JavaScript ES6+ quick reference: destructuring, spread operator, arrow functions, array methods, promises, async/await, and modules. - [TypeScript Cheat Sheet — Types & Generics Quick Reference](https://env.dev/cheatsheets/typescript-cheat-sheet): TypeScript quick reference: basic types, interfaces, generics, utility types, type guards, enums, and type assertions. - [SQL Cheat Sheet — Queries & Commands Quick Reference](https://env.dev/cheatsheets/sql-cheat-sheet): SQL quick reference: SELECT, JOINs, GROUP BY, subqueries, window functions, indexes, and data manipulation commands. - [Go (Golang) Cheat Sheet — Quick Reference](https://env.dev/cheatsheets/go-cheat-sheet): Go quick reference: types, structs, interfaces, goroutines, channels, error handling, slices, maps, and defer/panic/recover. - [Rust Cheat Sheet — Ownership & Types Quick Reference](https://env.dev/cheatsheets/rust-cheat-sheet): Rust quick reference: ownership, borrowing, lifetimes, traits, enums, pattern matching, Result/Option, and common macros. - [CSS Cheat Sheet — Flexbox, Grid & Selectors Quick Reference](https://env.dev/cheatsheets/css-cheat-sheet): CSS quick reference: Flexbox, Grid, selectors, units, CSS variables, media queries, and transitions. - [Linux Commands Cheat Sheet — Quick Reference](https://env.dev/cheatsheets/linux-cheat-sheet): Linux commands quick reference: file management, process control, networking, permissions, systemd, and disk usage. - [AWS CLI Cheat Sheet — EC2, S3 & IAM Quick Reference](https://env.dev/cheatsheets/aws-cli-cheat-sheet): AWS CLI quick reference: EC2, S3, IAM, Lambda, and CloudFormation commands with copy-paste examples, named profiles, and JMESPath --query filtering. - [Markdown Cheat Sheet — Syntax Quick Reference](https://env.dev/cheatsheets/markdown-cheat-sheet): Markdown syntax quick reference: headings, links, images, lists, code blocks, tables, and GitHub Flavored Markdown extensions. - [Vim Cheat Sheet — Commands & Motions Quick Reference](https://env.dev/cheatsheets/vim-cheat-sheet): Vim quick reference: modes, navigation, editing, search/replace, visual mode, registers, macros, and window management. - [MySQL Cheat Sheet — Commands & Queries Quick Reference](https://env.dev/cheatsheets/mysql-cheat-sheet): MySQL quick reference: data types, CRUD operations, JOINs, indexes, user management, backup/restore, and common functions. ## Comparisons - [Bun vs Deno vs Node.js: Which Runtime in 2026?](https://env.dev/comparisons/bun-vs-deno-vs-node): Compare Bun 1.3, Deno 2.7, and Node.js 24 LTS. Benchmarks for cold start, throughput, and install speed; how each handles .env files; and when to pick which. - [REST vs GraphQL: Which API Style Should You Use?](https://env.dev/comparisons/rest-vs-graphql): Compare REST and GraphQL APIs side by side. The trade-offs in performance, flexibility, caching, and developer experience, and how to choose. - [Docker vs Kubernetes: What's the Difference?](https://env.dev/comparisons/docker-vs-kubernetes): Understand the difference between Docker and Kubernetes. Docker builds and runs containers; Kubernetes orchestrates them at scale. Learn when to use each. - [npm vs yarn vs pnpm: Package Manager Comparison](https://env.dev/comparisons/npm-vs-yarn-vs-pnpm): Compare npm, yarn, and pnpm package managers. Benchmark install speed, disk usage, lockfile format, and monorepo support to pick the best one for your project. - [PostgreSQL vs MySQL: Which Database to Choose?](https://env.dev/comparisons/postgresql-vs-mysql): Compare PostgreSQL and MySQL databases. Analyze performance, features, JSON support, replication, and ecosystem to choose the right database for your project. - [Redis vs Memcached: In-Memory Caching Compared](https://env.dev/comparisons/redis-vs-memcached): Compare Redis and Memcached for caching. Evaluate data structures, persistence, clustering, and use cases to pick the right in-memory store. - [Nginx vs Apache: Web Server Comparison](https://env.dev/comparisons/nginx-vs-apache): Compare Nginx and Apache web servers. Evaluate performance, configuration, modules, reverse proxy capabilities, and resource usage. - [SQL vs NoSQL: How to Choose the Right Database](https://env.dev/comparisons/sql-vs-nosql): Compare SQL and NoSQL databases. Understand relational vs document/key-value/graph models, consistency guarantees, scalability, and when to use each. - [TypeScript vs JavaScript: Is TypeScript Worth It?](https://env.dev/comparisons/typescript-vs-javascript): Compare TypeScript and JavaScript. Evaluate type safety, developer experience, build tooling, ecosystem support, and migration strategies. - [Git Merge vs Rebase: When to Use Each](https://env.dev/comparisons/git-merge-vs-rebase): Compare git merge and git rebase strategies. Understand how each affects commit history, when to use which, and best practices for team workflows. - [Vite vs Webpack: Build Tool Comparison](https://env.dev/comparisons/vite-vs-webpack): Compare Vite and Webpack build tools. Evaluate dev server speed, build performance, configuration complexity, plugin ecosystems, and migration paths. ## Updates - [GPT-5.6: OpenAI's Sol, Terra, and Luna take aim at Fable 5](https://env.dev/updates/gpt-5-6): GPT-5.6 ships as three tiers — Sol ($5/$30), Terra ($2.50/$15), Luna ($1/$6). Sol Ultra tops TerminalBench 2.1 at 91.9%, past Claude Mythos 5's 88.0%. - [Claude Fable 5: Anthropic's Mythos-class model goes public](https://env.dev/updates/claude-fable-5): Claude Fable 5 tops SWE-Bench Pro at 80.3% and is the same model as Mythos 5 with safeguards on — not scaled down. Pricing, ranking, and access. - [Claude Agent SDK and `claude -p` move to a credit pool](https://env.dev/updates/anthropic-agent-sdk-credits): From June 15, 2026, Claude Agent SDK and `claude -p` stop drawing on subscription rate limits and start draining a separate monthly credit pool. ## Developer Tools - [JSON Formatter & Validator](https://env.dev/tools/json-formatter): Format, prettify, validate, and minify JSON online. Configurable indent and clear, descriptive errors on invalid JSON — runs entirely in your browser. - [SQL Formatter](https://env.dev/tools/sql-formatter): Format and beautify SQL for MySQL, PostgreSQL, SQLite, and SQL Server. Uppercase keywords, indent clauses, and make CTEs and stored procedures readable. - [Markdown Preview](https://env.dev/tools/markdown-preview): Preview GitHub-flavored Markdown as HTML in real time — headings, lists, tables, task lists, code, and blockquotes render instantly. Great for READMEs. - [Base64 Encode / Decode](https://env.dev/tools/base64-codec): Encode and decode Base64 and Base64URL strings online. Toggle between standard Base64 and URL-safe Base64URL with real-time conversion. - [URL Encode / Decode](https://env.dev/tools/url-codec): Encode and decode URLs with full percent-encoding support. Safely escape query strings, path segments, and form-data payloads for web APIs and HTTP requests. - [JWT Debugger](https://env.dev/tools/jwt-debugger): Decode, inspect and verify JSON Web Tokens. View claims with OIDC descriptions, verify HS256/RS256/ES256, and auto-fetch public keys from OIDC issuers. - [HTML Entity Encode / Decode](https://env.dev/tools/html-entity-codec): Encode and decode HTML entities online. Escape <, >, &, quotes, and non-ASCII Unicode for safe rendering in HTML, JSX, and email — runs in your browser. - [UUID Generator](https://env.dev/tools/uuid-generator): Generate v4 UUIDs online — bulk generation up to 1000 at once, instant copy to clipboard, RFC 4122 compliant. Uses crypto.randomUUID, runs in your browser. - [Hash Generator](https://env.dev/tools/hash-generator): Generate SHA-1, SHA-256, and SHA-512 hashes from any text or string. Browser-based cryptographic hashing for checksums and fingerprinting — nothing is uploaded. - [Lorem Ipsum Generator](https://env.dev/tools/lorem-ipsum-generator): Generate lorem ipsum placeholder text instantly. Pick paragraphs, sentences, or words — perfect for mocking layouts, design comps, and CMS content templates. - [Unix Timestamp Converter](https://env.dev/tools/timestamp-converter): Convert Unix timestamps to human-readable dates and back. Handles seconds, milliseconds, UTC, local time zones, ISO 8601, and relative times — fast and offline. - [Color Converter](https://env.dev/tools/color-converter): Convert colors between HEX, RGB, HSL, HSV, and OKLCH online. Live preview, named CSS colors, WCAG contrast check, and instant copy in any format — no signup. - [Number Base Converter](https://env.dev/tools/number-base-converter): Convert numbers between decimal, hexadecimal, octal, and binary instantly in your browser. Handy for debugging bitmasks, color hex codes, and chmod permissions. - [Text Case Converter](https://env.dev/tools/text-case-converter): Convert text between camelCase, PascalCase, snake_case, kebab-case, UPPER, lower, Title and Sentence case. - [Regex Tester](https://env.dev/tools/regex-tester): Test and debug JavaScript regular expressions online. Live match highlighting, capture-group inspection, flag support, and instant syntax-error feedback. - [Diff Checker](https://env.dev/tools/diff-checker): Compare two text blocks side-by-side and highlight inline differences. Word- and line-level diff for code, JSON, config files, and prose — runs in your browser. - [Cron Expression Parser](https://env.dev/tools/cron-parser): Parse and explain cron expressions in plain English. See upcoming run times, validate syntax, and understand schedules for crontab, Kubernetes, and CI jobs. - [YAML ↔ JSON Converter](https://env.dev/tools/yaml-json-converter): Convert YAML to JSON and JSON to YAML in your browser. Bidirectional conversion preserves nested structure and types — for Kubernetes manifests and CI configs. - [Password Generator](https://env.dev/tools/password-generator): Generate strong, random passwords and passphrases online. Strength meter, configurable character sets, and word-based passphrase mode. - [JSON to TypeScript](https://env.dev/tools/json-to-typescript): Convert JSON objects into TypeScript interfaces and types. Generate accurate types from API responses or sample data instantly — runs entirely in your browser. - [CSS Minifier / Beautifier](https://env.dev/tools/css-minifier): Minify and beautify CSS online. Strip whitespace and comments to shrink file size, or reformat compressed CSS for readability — runs entirely in your browser. - [QR Code Generator](https://env.dev/tools/qr-code-generator): Generate QR codes from any text or URL. Adjustable size to 512px, four error-correction levels, instant PNG and SVG download, and live preview — no tracking. - [Word Counter](https://env.dev/tools/word-counter): Count words, characters, sentences, and paragraphs as you type. Instantly estimates reading time — handy for essays, blog posts, and SEO-friendly snippets. - [IP Subnet Calculator](https://env.dev/tools/ip-subnet-calculator): Calculate IPv4 subnets, split networks into subnets, plan address space with visual binary breakdown and exportable subnet plans. - [cURL to Code Converter](https://env.dev/tools/curl-to-code): Convert cURL commands to Python, JavaScript, Go, PHP, and Ruby. Paste a curl request, get idiomatic client code instantly — runs entirely in your browser. - [JSON to CSV Converter](https://env.dev/tools/json-csv-converter): Convert JSON arrays to CSV and CSV to JSON online. Handles nested objects with automatic flattening. - [Markdown to HTML Converter](https://env.dev/tools/markdown-to-html): Convert Markdown to HTML with live preview. GitHub-flavored — tables, task lists, code fences, autolinks — with sanitized HTML output you can copy. - [HTML to Markdown Converter](https://env.dev/tools/html-to-markdown): Convert HTML to clean GitHub-flavored Markdown online. Handles headings, lists, links, images, code blocks, blockquotes, and tables — runs in your browser. - [Image to Base64 Converter](https://env.dev/tools/image-to-base64): Convert images to Base64 data URIs online. Drag and drop or upload any image to get Base64 encoded output. - [.gitignore Generator](https://env.dev/tools/gitignore-generator): Generate safe, thorough .gitignore files. Every output includes a safety baseline (OS files, editor swaps, logs, secrets) and covers 50+ languages. - [Dockerfile Generator](https://env.dev/tools/dockerfile-generator): Generate production-ready Dockerfiles for Node.js, Python, Go, Rust, Java, and more. Multi-stage builds, slim base images, and non-root user defaults built in. - [DNS Lookup](https://env.dev/tools/dns-lookup): Look up DNS records for any domain. Query A, AAAA, MX, TXT, NS, and CNAME records using DNS-over-HTTPS. - [TOML / JSON / YAML Converter](https://env.dev/tools/toml-converter): Convert between TOML, JSON, and YAML online. Bidirectional config conversion with live preview — paste a config, switch formats, runs entirely in your browser. - [JWT Generator](https://env.dev/tools/jwt-generator): Create and sign JSON Web Tokens with custom claims online. Supports HS256, HS384, and HS512 algorithms. - [Chmod Calculator](https://env.dev/tools/chmod-calculator): Visual file permission calculator. Convert between symbolic (rwxr-xr-x) and octal (755) notation, toggle setuid/setgid/sticky bits, and copy the chmod command. - [CSV Viewer & Editor](https://env.dev/tools/csv-viewer): View CSV files as sortable, searchable tables online. Paste or upload data, sort by any column, and scan large files — runs entirely in your browser. - [JSONPath Tester](https://env.dev/tools/jsonpath-tester): Test JSONPath expressions against JSON data online with live results and example queries. Filter, slice, and extract nodes — runs entirely in your browser. - [HTTP Header Analyzer](https://env.dev/tools/http-header-analyzer): Analyze HTTP response headers for security gaps. Audits HSTS, CSP, X-Frame-Options, Referrer-Policy, Permissions-Policy, and CORS — paste your raw headers. - [Meta Tag Generator (OpenGraph, Twitter, SEO)](https://env.dev/tools/meta-tag-generator): Generate OpenGraph, Twitter Card, and SEO meta tags. Enter title, description, URL, and image, then copy the HTML snippet. Optional JSON-LD. Browser-only. - [.env Builder](https://env.dev/tools/env-builder): Generate .env templates for Node.js, Docker, and AWS. Review defaults and loader instructions, then copy or download. - [.env Validator](https://env.dev/tools/env-validator): Check literal .env syntax, compare .env.example keys, and generate a values-free example. Review naming advice and secret patterns locally. - [.env Converter](https://env.dev/tools/env-converter): Paste a .env file, get the equivalent for Docker Compose, Kubernetes ConfigMap, Vercel CLI, AWS Parameter Store, GitHub Actions, or shell exports. Client-side. ## AI Resources - [Cursor](https://env.dev/ai/cursor): AI-native VS Code fork. Cursor 3 ships an Agents Window for parallel agents across local, worktrees, SSH, and cloud VMs. Composer 2 is the default model. - [Windsurf](https://env.dev/ai/windsurf): AI-powered IDE by Codeium with Cascade, an agentic LLM coding assistant that understands your full codebase. - [GitHub Copilot](https://env.dev/ai/github-copilot): AI pair programmer by GitHub. LLM-powered autocomplete, chat, and agent mode integrated into VS Code and JetBrains. - [Claude Code](https://env.dev/ai/claude-code): Anthropic's CLI-based agentic LLM coding tool. Terminal-first AI assistant for complex multi-file tasks. - [OpenCode](https://env.dev/ai/opencode): Open-source MIT-licensed terminal AI coding agent. BYO-model, MCP-native, signs in with your GitHub Copilot subscription. - [Codeium](https://env.dev/ai/codeium): Free AI code completion tool. Fast LLM-powered autocomplete for 70+ languages across all major editors. - [Amazon Q Developer](https://env.dev/ai/amazon-q-developer): AWS AI coding assistant. LLM-powered code completion, chat, and autonomous agent for AWS-integrated development. - [Lovable](https://env.dev/ai/lovable): AI-powered full-stack web app builder. Describe your app in plain English and get a deployable LLM-generated project. - [v0 by Vercel](https://env.dev/ai/v0): AI UI generator by Vercel. Generate React components and full pages from text prompts or images using LLMs. - [Bolt.new](https://env.dev/ai/bolt): AI full-stack app builder by StackBlitz. Build, edit, and deploy LLM-generated web apps entirely in the browser. - [Replit AI Agent](https://env.dev/ai/replit): AI coding agent that builds and deploys LLM-generated apps from natural language. Integrated cloud IDE with hosting. - [Cloudflare Workers AI](https://env.dev/ai/cloudflare-workers-ai): Run LLM and AI models at the edge with Cloudflare Workers. Serverless inference for text, image, and speech models. - [Emergent (E2B)](https://env.dev/ai/emergent): E2B (Emergent) gives AI agents secure cloud sandboxes — isolated Firecracker microVMs that boot in 200ms to run LLM-generated code, installs, and tool calls. - [Ollama](https://env.dev/ai/ollama): Local LLM runtime that wraps llama.cpp in a daemon and exposes an OpenAI-compatible API at localhost:11434. Pull a model, point a client. - [Open WebUI](https://env.dev/ai/open-webui): Self-hosted ChatGPT-style UI for local models. Pairs with Ollama, takes any OpenAI-compatible endpoint, ships RAG, RBAC, and SSO without paid tiers. ## AI Techniques & Guides - [Cursor Rules & Skills](https://env.dev/ai/cursor-rules-and-skills): Writing .cursorrules files and project-specific AI instructions for Cursor. Customize LLM behavior per-project. - [GitHub Copilot Extensions](https://env.dev/ai/copilot-extensions): Extend GitHub Copilot with third-party extensions and custom agents. Build domain-specific LLM capabilities. - [Claude Code MCP Servers](https://env.dev/ai/claude-code-mcp-servers): MCP in mid-2026: Linux Foundation governance, 10,000+ public servers, streamable HTTP setup for Claude Code, which servers to install, and the security model. - [System Prompts for Agentic Coding](https://env.dev/ai/system-prompts-agentic-coding): Effective system prompts for LLM coding agents. Structure, constraints, and output formatting for reliable code generation. - [AI Code Review Prompts](https://env.dev/ai/code-review-prompts): Prompts for LLM-powered code review. Catch bugs, security issues, and style problems with structured review prompts. - [AI Debugging Prompts](https://env.dev/ai/debugging-prompts): Structured prompts for debugging with LLMs. Reproduce, isolate, and fix bugs systematically using AI assistants. - [AI Architecture Prompts](https://env.dev/ai/architecture-prompts): Prompts for LLM-assisted software architecture design. System design, API design, and database schema generation. - [AI Test Generation Prompts](https://env.dev/ai/test-generation-prompts): Prompts for generating tests with LLMs. Unit tests, integration tests, and edge case coverage from code context. - [AI Refactoring Prompts](https://env.dev/ai/refactoring-prompts): Prompts for LLM-assisted refactoring. Extract functions, simplify logic, and improve code structure safely. - [AI Documentation Prompts](https://env.dev/ai/documentation-prompts): Prompts for generating documentation with LLMs. README files, API docs, and inline comments from source code. - [AI Commit Message Prompts](https://env.dev/ai/commit-message-prompts): Prompts for generating commit messages with LLMs. Conventional commits, meaningful descriptions from diffs. - [Chain-of-Thought for Code](https://env.dev/ai/chain-of-thought-coding): Use chain-of-thought prompting to improve LLM code generation. Break complex problems into reasoning steps. - [Context Management for AI Coding](https://env.dev/ai/context-management): Manage LLM context windows for AI coding — token budgets, file pruning, summarization, and retrieval that keep Claude, GPT-4, and Gemini focused on the task. - [Agentic Coding Workflows](https://env.dev/ai/agentic-workflows): Design effective workflows for autonomous LLM coding agents. Planning, execution, and verification patterns. - [Harness Engineering for AI Coding Agents](https://env.dev/ai/harness-engineering): Build everything around the LLM — tools, MCP, hooks, evaluators, memory, sandboxes — so an agent ships code instead of just generating it. - [Agent Skills and the SKILL.md Standard](https://env.dev/ai/agent-skills): Agent Skills are folders with a SKILL.md that teach AI agents workflows. Now an open standard adopted by 40+ tools — spec, marketplaces, and security. - [How AI Agents Get Compromised: 6 Attack Patterns](https://env.dev/ai/how-ai-agents-get-compromised): Real-world AI agent breaches and CVEs from 2024–2026 mapped to six attack patterns — EchoLeak, Clinejection, the Replit DB wipe — with primary sources. - [Agentic Coding Levels (Shapiro Five Levels)](https://env.dev/ai/agentic-coding-levels): Dan Shapiro's five-level autonomy ladder for AI coding, from spicy autocomplete to the dark software factory — modeled on NHTSA's driving levels. - [Multi-File Editing with AI](https://env.dev/ai/multi-file-editing): Techniques for LLM-assisted changes across multiple files. Coordinate edits, maintain consistency, and avoid drift. - [Test-Driven Development with AI](https://env.dev/ai/tdd-with-ai): Combine TDD methodology with LLM assistants. Write tests first, then use AI to implement passing code. - [Awesome AI Coding Lists](https://env.dev/ai/awesome-ai-coding): Twelve community-maintained GitHub awesome lists for AI/LLM coding in 2026 — tools, prompt collections, MCP servers, frameworks, and learning resources. - [AI Coding Communities](https://env.dev/ai/ai-coding-communities): Active communities for LLM-assisted development. Discord servers, subreddits, and forums for sharing prompts and workflows. - [AI & LLM Coding Model Comparison](https://env.dev/ai/ai-model-comparison): Compare 2026 coding LLMs: Claude Fable 5, GPT-5.6 Sol/Terra/Luna, Opus 4.7, Sonnet 4.6, Gemini 2.5, DeepSeek. Pricing, benchmarks, and use cases. - [Prompt Engineering for Developers](https://env.dev/ai/prompt-engineering-for-developers): Essential LLM prompt engineering techniques for software developers. Get better code output from any AI model. - [AI Coding Best Practices](https://env.dev/ai/ai-coding-best-practices): Best practices for working with LLM coding assistants. Review, test, and integrate AI-generated code safely. - [Best VS Code AI Extensions](https://env.dev/ai/vscode-ai-extensions): Top VS Code extensions for LLM-assisted development. Code completion, chat, testing, and documentation tools. - [AI Editor Comparison](https://env.dev/ai/ai-editor-comparison): Side-by-side comparison: Cursor vs GitHub Copilot vs Claude Code vs Windsurf. Features, pricing, and LLM models. - [LLM APIs for Developers](https://env.dev/ai/llm-api-for-developers): Using Claude, OpenAI, and Gemini APIs in code. Practical guide to integrating LLM APIs into developer tools and applications. ## Environment Variable Reference > 244 environment variables — what each means, where it's set, and how to use it. Full reference at https://env.dev/variables - [_HANDLER](https://env.dev/variables#_HANDLER): The handler entry point for the Lambda function in the format file.method (e.g., index.handler). - [_X_AMZN_TRACE_ID](https://env.dev/variables#_X_AMZN_TRACE_ID): The AWS X-Ray tracing header containing the trace ID, parent segment ID, and sampling decision. - [ALL_PROXY](https://env.dev/variables#ALL_PROXY): Specifies a proxy server for all protocols (HTTP, HTTPS, FTP, etc.). - [APPLICATIONINSIGHTS_CONNECTION_STRING](https://env.dev/variables#APPLICATIONINSIGHTS_CONNECTION_STRING): The connection string for Azure Application Insights, used for application performance monitoring and logging. - [AWS_ACCESS_KEY_ID](https://env.dev/variables/AWS_ACCESS_KEY_ID): The access key ID for AWS IAM user or role authentication. - [AWS_CODECOMMIT_PROFILE](https://env.dev/variables#AWS_CODECOMMIT_PROFILE): Specifies the AWS CLI profile to use for AWS CodeCommit git operations. - [AWS_CONFIG_FILE](https://env.dev/variables#AWS_CONFIG_FILE): Overrides the default location of the AWS CLI configuration file. - [AWS_CONTAINER_CREDENTIALS_RELATIVE_URI](https://env.dev/variables#AWS_CONTAINER_CREDENTIALS_RELATIVE_URI): A relative URI path used to retrieve temporary credentials from the ECS credential provider. - [AWS_DEFAULT_OUTPUT](https://env.dev/variables#AWS_DEFAULT_OUTPUT): Sets the default output format for AWS CLI commands. - [AWS_DEFAULT_REGION](https://env.dev/variables/AWS_DEFAULT_REGION): The default AWS region for CLI commands and SDK operations when no region is explicitly specified. - [AWS_DYNAMODB_TABLE](https://env.dev/variables#AWS_DYNAMODB_TABLE): An application-defined variable specifying the name of an Amazon DynamoDB table. - [AWS_EC2_METADATA_DISABLED](https://env.dev/variables#AWS_EC2_METADATA_DISABLED): When set to true, disables the use of the EC2 instance metadata service (IMDS) for credential retrieval. - [AWS_ECS_CLUSTER](https://env.dev/variables#AWS_ECS_CLUSTER): An application-defined variable specifying the name or ARN of an Amazon ECS cluster. - [AWS_ECS_TASK_DEFINITION](https://env.dev/variables#AWS_ECS_TASK_DEFINITION): An application-defined variable referencing the ECS task definition family name or ARN. - [AWS_ENDPOINT_URL](https://env.dev/variables#AWS_ENDPOINT_URL): Overrides the default AWS service endpoint URL. - [AWS_EXECUTION_ENV](https://env.dev/variables#AWS_EXECUTION_ENV): Identifies the Lambda runtime environment, such as AWS_Lambda_nodejs20.x or AWS_Lambda_python3.12. - [AWS_LAMBDA_FUNCTION_MEMORY_SIZE](https://env.dev/variables#AWS_LAMBDA_FUNCTION_MEMORY_SIZE): The amount of memory (in MB) allocated to the Lambda function. - [AWS_LAMBDA_FUNCTION_NAME](https://env.dev/variables#AWS_LAMBDA_FUNCTION_NAME): The name of the currently executing AWS Lambda function. - [AWS_LAMBDA_FUNCTION_VERSION](https://env.dev/variables#AWS_LAMBDA_FUNCTION_VERSION): The version of the currently executing Lambda function. - [AWS_LAMBDA_LOG_GROUP_NAME](https://env.dev/variables#AWS_LAMBDA_LOG_GROUP_NAME): The CloudWatch Logs log group name for the current Lambda function. - [AWS_LAMBDA_LOG_STREAM_NAME](https://env.dev/variables#AWS_LAMBDA_LOG_STREAM_NAME): The CloudWatch Logs log stream name for the current Lambda function invocation. - [AWS_LAMBDA_RUNTIME_API](https://env.dev/variables#AWS_LAMBDA_RUNTIME_API): The host and port of the Lambda Runtime API endpoint. - [AWS_MAX_ATTEMPTS](https://env.dev/variables#AWS_MAX_ATTEMPTS): Configures the maximum number of retry attempts for AWS SDK and CLI operations. - [AWS_PAGER](https://env.dev/variables#AWS_PAGER): Specifies the pager program used for AWS CLI output. - [AWS_PROFILE](https://env.dev/variables#AWS_PROFILE): Specifies the named profile from the AWS credentials and config files to use. - [AWS_REGION](https://env.dev/variables/AWS_REGION): The AWS region for SDK operations, taking precedence over AWS_DEFAULT_REGION when both are set. - [AWS_RETRY_MODE](https://env.dev/variables#AWS_RETRY_MODE): Specifies the retry strategy for AWS SDK operations. - [AWS_ROLE_ARN](https://env.dev/variables#AWS_ROLE_ARN): The Amazon Resource Name (ARN) of the IAM role to assume for cross-account access or temporary elevated permissions. - [AWS_S3_BUCKET](https://env.dev/variables#AWS_S3_BUCKET): A commonly used application-defined variable for specifying the target Amazon S3 bucket name. - [AWS_SDK_LOAD_CONFIG](https://env.dev/variables#AWS_SDK_LOAD_CONFIG): When set to a truthy value, instructs the AWS SDK for JavaScript v2 to load configuration from the shared config file (~/.aws/config) in addition to the cred… - [AWS_SECRET_ACCESS_KEY](https://env.dev/variables/AWS_SECRET_ACCESS_KEY): The secret access key paired with AWS_ACCESS_KEY_ID for signing AWS API requests. - [AWS_SESSION_TOKEN](https://env.dev/variables#AWS_SESSION_TOKEN): A temporary session token provided alongside temporary access credentials from AWS STS (Security Token Service). - [AWS_SHARED_CREDENTIALS_FILE](https://env.dev/variables#AWS_SHARED_CREDENTIALS_FILE): Overrides the default location of the shared credentials file that stores access key pairs for named profiles. - [AWS_SNS_TOPIC_ARN](https://env.dev/variables#AWS_SNS_TOPIC_ARN): The ARN of an Amazon SNS topic for publishing notifications. - [AWS_SQS_QUEUE_URL](https://env.dev/variables#AWS_SQS_QUEUE_URL): The URL of an Amazon SQS queue used by the application for message processing. - [AWS_STS_REGIONAL_ENDPOINTS](https://env.dev/variables#AWS_STS_REGIONAL_ENDPOINTS): Controls whether STS API calls use regional endpoints or the global endpoint (sts.amazonaws.com). - [AWS_WEB_IDENTITY_TOKEN_FILE](https://env.dev/variables#AWS_WEB_IDENTITY_TOKEN_FILE): The path to a file containing an OIDC web identity token, used for AssumeRoleWithWebIdentity. - [AWS_XRAY_DAEMON_ADDRESS](https://env.dev/variables#AWS_XRAY_DAEMON_ADDRESS): The IP address and port of the X-Ray daemon running in the Lambda execution environment. - [AZURE_AD_CLIENT_ID](https://env.dev/variables#AZURE_AD_CLIENT_ID): The Application (client) ID assigned to your app registration in Azure Active Directory. - [AZURE_AD_CLIENT_SECRET](https://env.dev/variables#AZURE_AD_CLIENT_SECRET): A client secret generated for your Azure AD app registration, used for service principal authentication. - [AZURE_AD_TENANT_ID](https://env.dev/variables#AZURE_AD_TENANT_ID): The Directory (tenant) ID of your Azure Active Directory instance. - [AZURE_AUTHORITY_HOST](https://env.dev/variables#AZURE_AUTHORITY_HOST): The Azure AD authority endpoint URL used for authentication. - [AZURE_CLIENT_CERTIFICATE_PATH](https://env.dev/variables#AZURE_CLIENT_CERTIFICATE_PATH): The file path to a PEM or PFX certificate used for certificate-based authentication with Azure AD. - [AZURE_CONTAINER_REGISTRY_NAME](https://env.dev/variables#AZURE_CONTAINER_REGISTRY_NAME): The name of your Azure Container Registry (ACR) instance. - [AZURE_CONTAINER_REGISTRY_PASSWORD](https://env.dev/variables#AZURE_CONTAINER_REGISTRY_PASSWORD): The admin password for Azure Container Registry, used for docker login authentication. - [AZURE_COSMOS_DB_CONNECTION_STRING](https://env.dev/variables#AZURE_COSMOS_DB_CONNECTION_STRING): The connection string for Azure Cosmos DB, including the account endpoint, key, and database information. - [AZURE_COSMOS_DB_KEY](https://env.dev/variables#AZURE_COSMOS_DB_KEY): The primary or secondary key for Azure Cosmos DB account authentication. - [AZURE_DEVOPS_ORG_URL](https://env.dev/variables#AZURE_DEVOPS_ORG_URL): The URL of your Azure DevOps organization, used by Azure DevOps REST APIs and CLI tools. - [AZURE_DEVOPS_PAT](https://env.dev/variables#AZURE_DEVOPS_PAT): A Personal Access Token for authenticating with Azure DevOps APIs and services. - [AZURE_EVENT_HUB_CONNECTION_STRING](https://env.dev/variables#AZURE_EVENT_HUB_CONNECTION_STRING): The connection string for Azure Event Hubs, used for high-throughput event streaming. - [AZURE_FEDERATED_TOKEN_FILE](https://env.dev/variables#AZURE_FEDERATED_TOKEN_FILE): The path to a file containing a federated identity token, used for workload identity federation. - [AZURE_FUNCTIONS_ENVIRONMENT](https://env.dev/variables#AZURE_FUNCTIONS_ENVIRONMENT): Specifies the hosting environment for Azure Functions, such as Development, Staging, or Production. - [AZURE_KEY_VAULT_NAME](https://env.dev/variables#AZURE_KEY_VAULT_NAME): The name of the Azure Key Vault resource. - [AZURE_KEY_VAULT_URL](https://env.dev/variables#AZURE_KEY_VAULT_URL): The full URI of the Azure Key Vault instance, used by the Key Vault SDK to connect and retrieve secrets, keys, and certificates. - [AZURE_OPENAI_API_KEY](https://env.dev/variables#AZURE_OPENAI_API_KEY): The API key for accessing Azure OpenAI Service endpoints. - [AZURE_OPENAI_ENDPOINT](https://env.dev/variables#AZURE_OPENAI_ENDPOINT): The endpoint URL for your Azure OpenAI Service resource. - [AZURE_REDIS_CACHE_HOST](https://env.dev/variables#AZURE_REDIS_CACHE_HOST): The hostname of the Azure Cache for Redis instance. - [AZURE_REDIS_CACHE_KEY](https://env.dev/variables#AZURE_REDIS_CACHE_KEY): The access key for Azure Cache for Redis instance authentication. - [AZURE_RESOURCE_GROUP](https://env.dev/variables#AZURE_RESOURCE_GROUP): The name of the Azure Resource Group that contains the target resources. - [AZURE_SERVICE_BUS_CONNECTION_STRING](https://env.dev/variables#AZURE_SERVICE_BUS_CONNECTION_STRING): The connection string for Azure Service Bus, including the namespace endpoint and shared access key. - [AZURE_SIGNALR_CONNECTION_STRING](https://env.dev/variables#AZURE_SIGNALR_CONNECTION_STRING): The connection string for Azure SignalR Service, used for real-time web communication. - [AZURE_SQL_CONNECTION_STRING](https://env.dev/variables#AZURE_SQL_CONNECTION_STRING): The ADO.NET or ODBC connection string for Azure SQL Database. - [AZURE_STORAGE_ACCOUNT](https://env.dev/variables#AZURE_STORAGE_ACCOUNT): The name of the Azure Storage account. - [AZURE_STORAGE_CONNECTION_STRING](https://env.dev/variables#AZURE_STORAGE_CONNECTION_STRING): A full connection string for Azure Storage that includes the account name, key, and endpoint information. - [AZURE_STORAGE_KEY](https://env.dev/variables#AZURE_STORAGE_KEY): The access key for your Azure Storage account, used for Shared Key authorization. - [AZURE_SUBSCRIPTION_ID](https://env.dev/variables#AZURE_SUBSCRIPTION_ID): The unique identifier for your Azure subscription. - [AZURE_WEBAPP_NAME](https://env.dev/variables#AZURE_WEBAPP_NAME): The name of the Azure App Service web application. - [AZURE_WEBAPP_RESOURCE_GROUP](https://env.dev/variables#AZURE_WEBAPP_RESOURCE_GROUP): The resource group containing the Azure App Service web application. - [AzureWebJobsStorage](https://env.dev/variables#AzureWebJobsStorage): The Azure Storage connection string used by Azure Functions for internal operations like managing triggers, logging, and function keys. - [BUILD_NUMBER](https://env.dev/variables#BUILD_NUMBER): The build number for the current Jenkins build, incrementing with each new build of the job. - [BUILD_URL](https://env.dev/variables#BUILD_URL): The full URL of the current Jenkins build, providing a direct link to the build's page in the Jenkins UI. - [BUN_INSTALL](https://env.dev/variables#BUN_INSTALL): The installation directory for Bun, the fast JavaScript runtime and package manager. - [CASSANDRA_CONTACT_POINTS](https://env.dev/variables#CASSANDRA_CONTACT_POINTS): A comma-separated list of Cassandra node addresses used as initial contact points for the driver to discover the cluster topology. - [CI](https://env.dev/variables#CI): A widely-adopted convention set to true by most CI/CD platforms to indicate that code is running in a continuous integration environment. - [CI_COMMIT_REF_NAME](https://env.dev/variables#CI_COMMIT_REF_NAME): The branch or tag name for which the GitLab CI/CD pipeline is running. - [CI_COMMIT_SHA](https://env.dev/variables#CI_COMMIT_SHA): The full commit SHA being built in a GitLab CI/CD pipeline. - [CI_JOB_TOKEN](https://env.dev/variables#CI_JOB_TOKEN): A temporary token generated for each GitLab CI/CD job, used to authenticate with the GitLab API, container registry, and package registry. - [CI_PIPELINE_ID](https://env.dev/variables#CI_PIPELINE_ID): The unique ID of the current GitLab CI/CD pipeline. - [CI_PROJECT_DIR](https://env.dev/variables#CI_PROJECT_DIR): The full path to the directory where the repository is cloned in a GitLab CI/CD job. - [CIRCLE_BRANCH](https://env.dev/variables#CIRCLE_BRANCH): The name of the Git branch being built in CircleCI. - [CIRCLE_BUILD_NUM](https://env.dev/variables#CIRCLE_BUILD_NUM): The number of the current CircleCI build, incrementing for each new job run. - [CIRCLECI](https://env.dev/variables#CIRCLECI): Set to true when running in a CircleCI environment. - [CLOUD_SQL_CONNECTION_NAME](https://env.dev/variables#CLOUD_SQL_CONNECTION_NAME): The connection name for a Cloud SQL instance in the format project:region:instance. - [CLOUDSDK_AUTH_CREDENTIAL_FILE_OVERRIDE](https://env.dev/variables#CLOUDSDK_AUTH_CREDENTIAL_FILE_OVERRIDE): Overrides the credential file used by the gcloud CLI, taking precedence over the logged-in user's credentials. - [CLOUDSDK_COMPUTE_REGION](https://env.dev/variables#CLOUDSDK_COMPUTE_REGION): Sets the default Compute Engine region for the gcloud CLI. - [CLOUDSDK_COMPUTE_ZONE](https://env.dev/variables#CLOUDSDK_COMPUTE_ZONE): Sets the default Compute Engine zone for the gcloud CLI. - [CLOUDSDK_CORE_PROJECT](https://env.dev/variables#CLOUDSDK_CORE_PROJECT): Sets the default project for the Google Cloud SDK (gcloud CLI). - [COLORTERM](https://env.dev/variables#COLORTERM): Indicates the color capabilities of the terminal. - [COMPOSE_FILE](https://env.dev/variables#COMPOSE_FILE): Specifies the path to one or more Compose files, separated by the OS path separator (: on Linux/macOS, ; on Windows). - [COMPOSE_HTTP_TIMEOUT](https://env.dev/variables#COMPOSE_HTTP_TIMEOUT): Configures the timeout in seconds for HTTP requests made by Docker Compose to the Docker daemon. - [COMPOSE_PROFILES](https://env.dev/variables#COMPOSE_PROFILES): A comma-separated list of active Compose profiles. - [COMPOSE_PROJECT_NAME](https://env.dev/variables/COMPOSE_PROJECT_NAME): Sets the project name for Docker Compose, which is used as a prefix for container names, network names, and volume names. - [CURL_CA_BUNDLE](https://env.dev/variables#CURL_CA_BUNDLE): Specifies the path to a CA certificate bundle file used by curl for TLS verification. - [DATABASE_URL](https://env.dev/variables/DATABASE_URL): A universal database connection string following the URI format protocol://user:password@host:port/database. - [DENO_DIR](https://env.dev/variables#DENO_DIR): The root directory for Deno's cache, including downloaded modules, compiled code, and other cached data. - [DEPLOY_URL](https://env.dev/variables#DEPLOY_URL): The unique URL for the current Netlify deploy. - [DISPLAY](https://env.dev/variables#DISPLAY): Identifies the X11 display server to connect to for graphical applications. - [DOCKER_BUILDKIT](https://env.dev/variables/DOCKER_BUILDKIT): When set to 1, enables BuildKit as the default builder for docker build commands. - [DOCKER_CERT_PATH](https://env.dev/variables#DOCKER_CERT_PATH): The path to a directory containing TLS certificates (ca.pem, cert.pem, key.pem) for authenticating with a TLS-secured Docker daemon. - [DOCKER_CLI_EXPERIMENTAL](https://env.dev/variables#DOCKER_CLI_EXPERIMENTAL): Enables or disables experimental CLI features. - [DOCKER_CONFIG](https://env.dev/variables#DOCKER_CONFIG): Overrides the default location of the Docker CLI configuration directory. - [DOCKER_CONTENT_TRUST](https://env.dev/variables#DOCKER_CONTENT_TRUST): When set to 1, enables Docker Content Trust (DCT) which enforces image signing and verification using Notary. - [DOCKER_DEFAULT_PLATFORM](https://env.dev/variables#DOCKER_DEFAULT_PLATFORM): Sets the default platform for building and pulling images when the platform is not specified. - [DOCKER_HIDE_LEGACY_COMMANDS](https://env.dev/variables#DOCKER_HIDE_LEGACY_COMMANDS): When set to any non-empty value, hides legacy top-level Docker commands from the help output, showing only the modern management commands (docker container,… - [DOCKER_HOST](https://env.dev/variables/DOCKER_HOST): Specifies the Docker daemon socket to connect to. - [DOCKER_SCAN_SUGGEST](https://env.dev/variables#DOCKER_SCAN_SUGGEST): Controls whether Docker displays suggestions to scan images for vulnerabilities after building. - [DOCKER_TLS_VERIFY](https://env.dev/variables#DOCKER_TLS_VERIFY): When set to any non-empty value, enables TLS verification for connections to the Docker daemon. - [ECS_CONTAINER_METADATA_URI](https://env.dev/variables#ECS_CONTAINER_METADATA_URI): The URI for the ECS container metadata endpoint (version 3). - [ECS_CONTAINER_METADATA_URI_V4](https://env.dev/variables#ECS_CONTAINER_METADATA_URI_V4): The URI for the ECS container metadata endpoint version 4, providing enhanced metadata including task-level network stats and additional container information. - [EDITOR](https://env.dev/variables#EDITOR): Specifies the default text editor for command-line programs. - [ELASTICSEARCH_URL](https://env.dev/variables#ELASTICSEARCH_URL): The URL of the Elasticsearch cluster endpoint. - [FIREBASE_CONFIG](https://env.dev/variables#FIREBASE_CONFIG): A JSON string containing Firebase configuration automatically set in Cloud Functions for Firebase runtime. - [FIREBASE_TOKEN](https://env.dev/variables#FIREBASE_TOKEN): A CI token for authenticating Firebase CLI commands in non-interactive environments. - [FORCE_COLOR](https://env.dev/variables#FORCE_COLOR): Forces color output in programs that support this convention, overriding automatic terminal detection. - [FUNCTION_SIGNATURE_TYPE](https://env.dev/variables#FUNCTION_SIGNATURE_TYPE): Specifies the signature type of the Cloud Function — either http for HTTP-triggered functions or event for event-triggered functions, or cloudevent for Cloud… - [FUNCTION_TARGET](https://env.dev/variables#FUNCTION_TARGET): Specifies the name of the exported function to invoke in Google Cloud Functions (2nd gen) and Cloud Functions for Firebase. - [FUNCTIONS_WORKER_RUNTIME](https://env.dev/variables#FUNCTIONS_WORKER_RUNTIME): Specifies the language runtime for Azure Functions, such as node, python, dotnet, java, or powershell. - [GCLOUD_PROJECT](https://env.dev/variables#GCLOUD_PROJECT): An alternative name for specifying the Google Cloud project ID. - [GCLOUD_SERVICE_KEY](https://env.dev/variables#GCLOUD_SERVICE_KEY): A convention used by some CI/CD tools to store the raw JSON content of a Google Cloud service account key for authentication. - [GCP_SERVICE_ACCOUNT_KEY](https://env.dev/variables#GCP_SERVICE_ACCOUNT_KEY): A convention used by some CI/CD platforms and tools to store the base64-encoded or raw JSON content of a Google Cloud service account key. - [GCS_BUCKET](https://env.dev/variables#GCS_BUCKET): An application-defined variable specifying the Google Cloud Storage bucket name to use. - [GITHUB_ACTIONS](https://env.dev/variables#GITHUB_ACTIONS): Set to true when running in GitHub Actions. - [GITHUB_ACTOR](https://env.dev/variables#GITHUB_ACTOR): The username of the person or app that triggered the workflow. - [GITHUB_API_URL](https://env.dev/variables#GITHUB_API_URL): The URL of the GitHub REST API. - [GITHUB_BASE_REF](https://env.dev/variables#GITHUB_BASE_REF): The base ref (target branch) of a pull request. - [GITHUB_ENV](https://env.dev/variables#GITHUB_ENV): The path to a file used to set environment variables for subsequent steps in a GitHub Actions job. - [GITHUB_EVENT_NAME](https://env.dev/variables#GITHUB_EVENT_NAME): The name of the event that triggered the workflow, such as push, pull_request, schedule, or workflow_dispatch. - [GITHUB_HEAD_REF](https://env.dev/variables#GITHUB_HEAD_REF): The head ref (source branch) of a pull request. - [GITHUB_OUTPUT](https://env.dev/variables#GITHUB_OUTPUT): The path to a file used to set step outputs in GitHub Actions. - [GITHUB_REF](https://env.dev/variables#GITHUB_REF): The fully qualified ref that triggered the workflow, such as refs/heads/main for branch pushes, refs/tags/v1.0.0 for tag pushes, or refs/pull/42/merge for pu… - [GITHUB_REPOSITORY](https://env.dev/variables#GITHUB_REPOSITORY): The owner and repository name in the format owner/repo. - [GITHUB_RUN_ID](https://env.dev/variables#GITHUB_RUN_ID): A unique number for each workflow run within a repository. - [GITHUB_SERVER_URL](https://env.dev/variables#GITHUB_SERVER_URL): The URL of the GitHub server. - [GITHUB_SHA](https://env.dev/variables#GITHUB_SHA): The commit SHA that triggered the workflow. - [GITHUB_TOKEN](https://env.dev/variables#GITHUB_TOKEN): An automatically generated token for authenticating GitHub API requests within a workflow. - [GITHUB_WORKFLOW](https://env.dev/variables#GITHUB_WORKFLOW): The name of the workflow as defined in the workflow YAML file. - [GITHUB_WORKSPACE](https://env.dev/variables#GITHUB_WORKSPACE): The default working directory on the runner for steps in a job. - [GITLAB_CI](https://env.dev/variables#GITLAB_CI): Set to true when running in GitLab CI/CD pipelines. - [GOOGLE_API_KEY](https://env.dev/variables#GOOGLE_API_KEY): An API key for accessing Google APIs that support API key authentication. - [GOOGLE_APPLICATION_CREDENTIALS](https://env.dev/variables/GOOGLE_APPLICATION_CREDENTIALS): The file path to a Google Cloud service account key JSON file. - [GOOGLE_CLOUD_KEYFILE_JSON](https://env.dev/variables#GOOGLE_CLOUD_KEYFILE_JSON): Contains the full JSON content of a service account key, as an alternative to referencing a file via GOOGLE_APPLICATION_CREDENTIALS. - [GOOGLE_CLOUD_PROJECT](https://env.dev/variables#GOOGLE_CLOUD_PROJECT): The Google Cloud project ID to use as the default for API requests. - [GOOGLE_CLOUD_QUOTA_PROJECT](https://env.dev/variables#GOOGLE_CLOUD_QUOTA_PROJECT): Specifies the Google Cloud project to bill for API quota and usage when different from the authenticated project. - [GOOGLE_CLOUD_REGION](https://env.dev/variables#GOOGLE_CLOUD_REGION): The default Google Cloud region for deploying and managing regional resources. - [GPG_TTY](https://env.dev/variables#GPG_TTY): Specifies the terminal device for GPG pinentry prompts. - [HOME](https://env.dev/variables/HOME): The absolute path to the current user's home directory. - [HOST](https://env.dev/variables#HOST): Specifies the hostname or IP address a web server should bind to. - [HOSTNAME](https://env.dev/variables#HOSTNAME): The network hostname of the current machine. - [HTTP_PROXY](https://env.dev/variables/HTTP_PROXY): Specifies the proxy server URL for HTTP requests. - [HTTPS_PROXY](https://env.dev/variables/HTTPS_PROXY): Specifies the proxy server URL for HTTPS requests. - [IDENTITY_ENDPOINT](https://env.dev/variables#IDENTITY_ENDPOINT): The endpoint URL for the Azure Identity token service, replacing the older MSI_ENDPOINT. - [IDENTITY_HEADER](https://env.dev/variables#IDENTITY_HEADER): A secret header value that must be included in requests to the IDENTITY_ENDPOINT to prevent server-side request forgery (SSRF) attacks. - [JAVA_HOME](https://env.dev/variables/JAVA_HOME): The path to the root of a JDK installation. - [JENKINS_HOME](https://env.dev/variables#JENKINS_HOME): The absolute path to the Jenkins home directory on the controller, where Jenkins stores its configuration, job definitions, and build data. - [JENKINS_URL](https://env.dev/variables#JENKINS_URL): The full URL of the Jenkins server, including the port number. - [JOB_NAME](https://env.dev/variables#JOB_NAME): The name of the Jenkins job currently being executed, including the folder path if the job is inside a folder. - [K_CONFIGURATION](https://env.dev/variables#K_CONFIGURATION): The name of the Cloud Run configuration that created the current revision. - [K_REVISION](https://env.dev/variables#K_REVISION): The name of the Cloud Run revision currently being executed. - [K_SERVICE](https://env.dev/variables#K_SERVICE): The name of the Cloud Run service currently being executed. - [LAMBDA_RUNTIME_DIR](https://env.dev/variables#LAMBDA_RUNTIME_DIR): The path to the runtime libraries directory in the Lambda execution environment. - [LAMBDA_TASK_ROOT](https://env.dev/variables#LAMBDA_TASK_ROOT): The path to the Lambda function code directory. - [LANG](https://env.dev/variables/LANG): Sets the default locale for all locale categories that are not explicitly set by a more specific LC_* variable. - [LC_ALL](https://env.dev/variables#LC_ALL): Overrides all other LC_* locale variables and LANG. - [LC_CTYPE](https://env.dev/variables#LC_CTYPE): Determines the locale used for character classification and case conversion. - [LOGNAME](https://env.dev/variables#LOGNAME): The login name of the user, set by the login process. - [MONGO_URL](https://env.dev/variables#MONGO_URL): An alternative name for the MongoDB connection URI, commonly used by Meteor.js and some older Node.js applications. - [MONGODB_URI](https://env.dev/variables#MONGODB_URI): The MongoDB connection string following the mongodb:// or mongodb+srv:// URI format. - [MSI_ENDPOINT](https://env.dev/variables#MSI_ENDPOINT): The endpoint URL for the Azure Managed Service Identity (MSI) token service, used by older versions of the Azure Identity SDK. - [MSI_SECRET](https://env.dev/variables#MSI_SECRET): The secret value used to authenticate requests to the MSI_ENDPOINT for obtaining managed identity tokens. - [MSSQL_SA_PASSWORD](https://env.dev/variables#MSSQL_SA_PASSWORD): The system administrator (SA) password for Microsoft SQL Server. - [MYSQL_DATABASE](https://env.dev/variables#MYSQL_DATABASE): The name of the MySQL database to use. - [MYSQL_HOST](https://env.dev/variables#MYSQL_HOST): The hostname or IP address of the MySQL server. - [MYSQL_PASSWORD](https://env.dev/variables#MYSQL_PASSWORD): The password for the MySQL user specified by MYSQL_USER. - [MYSQL_PORT](https://env.dev/variables#MYSQL_PORT): The port number for the MySQL server connection. - [MYSQL_ROOT_PASSWORD](https://env.dev/variables#MYSQL_ROOT_PASSWORD): Sets the root password for a MySQL server. - [MYSQL_USER](https://env.dev/variables#MYSQL_USER): The username for MySQL authentication. - [NETLIFY](https://env.dev/variables#NETLIFY): Set to true when the build is running on Netlify. - [NO_COLOR](https://env.dev/variables#NO_COLOR): When set to any non-empty value, disables color output in programs that respect this convention. - [NO_PROXY](https://env.dev/variables/NO_PROXY): A comma-separated list of hostnames, domain suffixes, or IP addresses that should bypass the proxy. - [NODE_DEBUG](https://env.dev/variables#NODE_DEBUG): A comma-separated list of core Node.js module names to enable debug output for. - [NODE_ENV](https://env.dev/variables/NODE_ENV): Specifies the environment in which the Node.js application is running. - [NODE_EXTRA_CA_CERTS](https://env.dev/variables#NODE_EXTRA_CA_CERTS): Path to a PEM file containing one or more extra certificate authority certificates to trust when making TLS connections. - [NODE_ICU_DATA](https://env.dev/variables#NODE_ICU_DATA): Path to ICU (International Components for Unicode) data for full internationalization support. - [NODE_NO_WARNINGS](https://env.dev/variables#NODE_NO_WARNINGS): When set to 1, suppresses all Node.js process warnings including deprecation warnings, experimental feature warnings, and other runtime warnings. - [NODE_OPTIONS](https://env.dev/variables/NODE_OPTIONS): A space-separated list of command-line options that are applied when starting any Node.js process. - [NODE_PATH](https://env.dev/variables#NODE_PATH): A colon-delimited (semicolon on Windows) list of directories to search for modules when using require(). - [NODE_PENDING_DEPRECATION](https://env.dev/variables#NODE_PENDING_DEPRECATION): When set to 1, emits pending deprecation warnings which are off by default. - [NODE_REPL_HISTORY](https://env.dev/variables#NODE_REPL_HISTORY): Path to the file where Node.js REPL command history is stored. - [NODE_TLS_REJECT_UNAUTHORIZED](https://env.dev/variables#NODE_TLS_REJECT_UNAUTHORIZED): When set to 0, disables TLS certificate verification for all outgoing HTTPS connections. - [npm_config_registry](https://env.dev/variables#npm_config_registry): Specifies the npm registry URL used for package installation and publishing. - [npm_package_name](https://env.dev/variables#npm_package_name): Automatically set by npm when running scripts defined in package.json. - [npm_package_version](https://env.dev/variables#npm_package_version): Automatically set by npm when running scripts, containing the version field from the package's package.json. - [NPM_TOKEN](https://env.dev/variables#NPM_TOKEN): An authentication token for the npm registry, used for publishing packages and accessing private packages. - [OLDPWD](https://env.dev/variables#OLDPWD): The absolute path of the previous working directory. - [PAGER](https://env.dev/variables#PAGER): Specifies the default pager program used for displaying long output. - [PATH](https://env.dev/variables/PATH): A colon-delimited list of directories the shell searches for executable programs. - [PGCONNECT_TIMEOUT](https://env.dev/variables#PGCONNECT_TIMEOUT): The maximum time in seconds to wait for a connection to the PostgreSQL server. - [PGDATABASE](https://env.dev/variables#PGDATABASE): The name of the PostgreSQL database to connect to. - [PGHOST](https://env.dev/variables#PGHOST): The hostname or IP address of the PostgreSQL server. - [PGPASSWORD](https://env.dev/variables#PGPASSWORD): The password for PostgreSQL authentication. - [PGPORT](https://env.dev/variables#PGPORT): The port number to connect to on the PostgreSQL server. - [PGSSLMODE](https://env.dev/variables#PGSSLMODE): Controls the SSL/TLS behavior for PostgreSQL connections. - [PGUSER](https://env.dev/variables#PGUSER): The username for PostgreSQL authentication. - [PNPM_HOME](https://env.dev/variables#PNPM_HOME): The directory where pnpm stores globally installed packages and its own binaries. - [PORT](https://env.dev/variables/PORT): A widely used convention for specifying the port number a web server should listen on. - [PORT](https://env.dev/variables#PORT): The port that Cloud Run injects for your container to listen on. - [PUBSUB_SUBSCRIPTION](https://env.dev/variables#PUBSUB_SUBSCRIPTION): An application-defined variable specifying the Google Cloud Pub/Sub subscription name for consuming messages. - [PUBSUB_TOPIC](https://env.dev/variables#PUBSUB_TOPIC): An application-defined variable specifying the Google Cloud Pub/Sub topic name to publish messages to. - [PWD](https://env.dev/variables#PWD): The absolute path of the current working directory. - [PYTHONPATH](https://env.dev/variables/PYTHONPATH): Extra directories Python prepends to sys.path, the module import search path. - [REDIS_HOST](https://env.dev/variables#REDIS_HOST): The hostname or IP address of the Redis server. - [REDIS_PASSWORD](https://env.dev/variables#REDIS_PASSWORD): The password for authenticating with a Redis server using the AUTH command. - [REDIS_PORT](https://env.dev/variables#REDIS_PORT): The port number for the Redis server connection. - [REDIS_URL](https://env.dev/variables/REDIS_URL): The Redis connection URL following the redis:// or rediss:// (TLS) URI format. - [REQUESTS_CA_BUNDLE](https://env.dev/variables#REQUESTS_CA_BUNDLE): The path to a CA certificate bundle file used by the Python requests library and other Python HTTP clients for TLS verification. - [SHELL](https://env.dev/variables#SHELL): The absolute path to the user's default login shell as specified in /etc/passwd. - [SHLVL](https://env.dev/variables#SHLVL): Tracks the nesting level of shell instances. - [SQLITE_DATABASE](https://env.dev/variables#SQLITE_DATABASE): An application-defined variable specifying the file path to a SQLite database file. - [SSH_AGENT_PID](https://env.dev/variables#SSH_AGENT_PID): The process ID of the running SSH authentication agent. - [SSH_AUTH_SOCK](https://env.dev/variables#SSH_AUTH_SOCK): The Unix socket path for communicating with the SSH authentication agent (ssh-agent). - [SSL_CERT_FILE](https://env.dev/variables#SSL_CERT_FILE): The path to a file containing trusted CA certificates in PEM format. - [TERM](https://env.dev/variables#TERM): Identifies the type of terminal emulator being used, which determines how programs output escape sequences for colors, cursor movement, and other terminal fe… - [TERM_PROGRAM](https://env.dev/variables#TERM_PROGRAM): Identifies the terminal emulator program being used. - [TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE](https://env.dev/variables#TESTCONTAINERS_DOCKER_SOCKET_OVERRIDE): Overrides the Docker socket path used by the Testcontainers library for integration testing. - [TMPDIR](https://env.dev/variables#TMPDIR): Specifies the directory for temporary files. - [TRAVIS](https://env.dev/variables#TRAVIS): Set to true when running in Travis CI. - [TRAVIS_BRANCH](https://env.dev/variables#TRAVIS_BRANCH): The name of the branch being built in Travis CI. - [TZ](https://env.dev/variables/TZ): Sets the timezone for the process, affecting how times are displayed and how time-related functions operate. - [USER](https://env.dev/variables#USER): The username of the currently logged-in user. - [UV_THREADPOOL_SIZE](https://env.dev/variables#UV_THREADPOOL_SIZE): Sets the number of threads in the libuv thread pool used for asynchronous I/O operations like file system access, DNS lookups, and crypto operations. - [VERCEL](https://env.dev/variables#VERCEL): Set to 1 when the application is running on Vercel's platform. - [VERCEL_ENV](https://env.dev/variables#VERCEL_ENV): The Vercel environment the deployment is running in — production, preview, or development. - [VERCEL_URL](https://env.dev/variables#VERCEL_URL): The URL of the current Vercel deployment, without the protocol prefix. - [VISUAL](https://env.dev/variables#VISUAL): Specifies the preferred visual (full-screen) editor. - [WAYLAND_DISPLAY](https://env.dev/variables#WAYLAND_DISPLAY): Identifies the Wayland compositor socket for graphical applications running under the Wayland display protocol. - [WEBSITE_HOSTNAME](https://env.dev/variables#WEBSITE_HOSTNAME): The default hostname of the Azure App Service instance, automatically set by the runtime. - [WEBSITE_INSTANCE_ID](https://env.dev/variables#WEBSITE_INSTANCE_ID): The unique instance ID of the current Azure App Service VM instance. - [WEBSITE_SITE_NAME](https://env.dev/variables#WEBSITE_SITE_NAME): Automatically set by Azure App Service to the name of the web app. - [XDG_CACHE_HOME](https://env.dev/variables#XDG_CACHE_HOME): The base directory for user-specific non-essential cached data, as defined by the XDG Base Directory Specification. - [XDG_CONFIG_HOME](https://env.dev/variables#XDG_CONFIG_HOME): The base directory for user-specific configuration files, as defined by the XDG Base Directory Specification. - [XDG_DATA_HOME](https://env.dev/variables#XDG_DATA_HOME): The base directory for user-specific data files, as defined by the XDG Base Directory Specification. - [XDG_RUNTIME_DIR](https://env.dev/variables#XDG_RUNTIME_DIR): The base directory for user-specific runtime files like sockets, named pipes, and other non-essential runtime data. - [XDG_STATE_HOME](https://env.dev/variables#XDG_STATE_HOME): The base directory for user-specific state data that should persist between application restarts but is not important enough for backup. - [YARN_CACHE_FOLDER](https://env.dev/variables#YARN_CACHE_FOLDER): Overrides the default location where Yarn stores downloaded package tarballs. ## Programming Constants Reference > 222 programming constants — values, types, and usage across languages. Full reference at https://env.dev/constants - [__debug__](https://env.dev/constants#__debug__): A boolean constant that is True if Python was not started with an -O (optimize) flag. - [100 Continue](https://env.dev/constants#100 Continue): The server has received the request headers and the client should proceed to send the request body. - [101 Switching Protocols](https://env.dev/constants#101 Switching Protocols): The server understands and is willing to comply with the client's request to switch protocols. - [102 Processing](https://env.dev/constants#102 Processing): The server has received and is processing the request, but no response is available yet. - [103 Early Hints](https://env.dev/constants#103 Early Hints): Used to return some response headers before the final HTTP message. - [200 OK](https://env.dev/constants#200 OK): The request has succeeded. - [201 Created](https://env.dev/constants#201 Created): The request has been fulfilled and has resulted in one or more new resources being created. - [202 Accepted](https://env.dev/constants#202 Accepted): The request has been accepted for processing, but the processing has not been completed. - [203 Non-Authoritative Information](https://env.dev/constants#203 Non-Authoritative Information): The request was successful but the returned metadata may be from a local or third-party copy rather than the origin server. - [204 No Content](https://env.dev/constants#204 No Content): The server has successfully fulfilled the request and there is no additional content to send in the response body. - [205 Reset Content](https://env.dev/constants#205 Reset Content): The server has fulfilled the request and the user agent should reset the document view that caused the request. - [206 Partial Content](https://env.dev/constants#206 Partial Content): The server is delivering only part of the resource due to a Range header sent by the client. - [207 Multi-Status](https://env.dev/constants#207 Multi-Status): Conveys information about multiple resources in situations where multiple status codes might be appropriate. - [300 Multiple Choices](https://env.dev/constants#300 Multiple Choices): The request has more than one possible response and the user or user agent should choose one. - [301 Moved Permanently](https://env.dev/constants#301 Moved Permanently): The resource has been permanently moved to a new URI given by the Location header. - [302 Found](https://env.dev/constants#302 Found): The resource resides temporarily at a different URI given by the Location header. - [303 See Other](https://env.dev/constants#303 See Other): The server is redirecting the client to a different resource using GET, typically after a POST or PUT. - [304 Not Modified](https://env.dev/constants#304 Not Modified): The resource has not been modified since the version specified by the request headers (If-Modified-Since or If-None-Match). - [307 Temporary Redirect](https://env.dev/constants#307 Temporary Redirect): The resource resides temporarily at a different URI. - [308 Permanent Redirect](https://env.dev/constants#308 Permanent Redirect): The resource has been permanently moved to a new URI. - [400 Bad Request](https://env.dev/constants#400 Bad Request): The server cannot process the request due to something perceived to be a client error, such as malformed syntax, invalid request framing, or deceptive reques… - [401 Unauthorized](https://env.dev/constants#401 Unauthorized): The request requires user authentication. - [402 Payment Required](https://env.dev/constants#402 Payment Required): Reserved for future use. - [403 Forbidden](https://env.dev/constants#403 Forbidden): The server understood the request but refuses to authorize it. - [404 Not Found](https://env.dev/constants#404 Not Found): The server cannot find the requested resource. - [405 Method Not Allowed](https://env.dev/constants#405 Method Not Allowed): The HTTP method used is not supported for the requested resource. - [406 Not Acceptable](https://env.dev/constants#406 Not Acceptable): The server cannot produce a response matching the list of acceptable values defined in the request's Accept headers (content negotiation). - [407 Proxy Authentication Required](https://env.dev/constants#407 Proxy Authentication Required): Similar to 401 but indicates that the client must first authenticate with the proxy. - [408 Request Timeout](https://env.dev/constants#408 Request Timeout): The server timed out waiting for the request. - [409 Conflict](https://env.dev/constants#409 Conflict): The request conflicts with the current state of the target resource. - [410 Gone](https://env.dev/constants#410 Gone): The resource is no longer available and will not be available again. - [411 Length Required](https://env.dev/constants#411 Length Required): The server refuses the request because the Content-Length header is not defined and the server requires it. - [412 Precondition Failed](https://env.dev/constants#412 Precondition Failed): One or more conditions in the request header fields (such as If-Match or If-Unmodified-Since) evaluated to false. - [413 Payload Too Large](https://env.dev/constants#413 Payload Too Large): The request entity is larger than the server is willing or able to process. - [414 URI Too Long](https://env.dev/constants#414 URI Too Long): The URI provided was too long for the server to process. - [415 Unsupported Media Type](https://env.dev/constants#415 Unsupported Media Type): The server refuses the request because the payload format is not supported. - [416 Range Not Satisfiable](https://env.dev/constants#416 Range Not Satisfiable): The client has asked for a portion of the file using the Range header, but the server cannot supply that portion. - [417 Expectation Failed](https://env.dev/constants#417 Expectation Failed): The server cannot meet the requirements of the Expect request-header field. - [418 I'm a Teapot](https://env.dev/constants#418 I'm a Teapot): An April Fools' joke from RFC 2324 (Hyper Text Coffee Pot Control Protocol). - [421 Misdirected Request](https://env.dev/constants#421 Misdirected Request): The request was directed at a server that is not able to produce a response. - [422 Unprocessable Entity](https://env.dev/constants#422 Unprocessable Entity): The server understands the content type and syntax of the request, but was unable to process the contained instructions. - [423 Locked](https://env.dev/constants#423 Locked): The resource that is being accessed is locked. - [424 Failed Dependency](https://env.dev/constants#424 Failed Dependency): The request failed because it depended on another request that failed. - [425 Too Early](https://env.dev/constants#425 Too Early): The server is unwilling to risk processing a request that might be replayed. - [426 Upgrade Required](https://env.dev/constants#426 Upgrade Required): The server refuses to perform the request using the current protocol but might do so after the client upgrades to a different protocol. - [428 Precondition Required](https://env.dev/constants#428 Precondition Required): The origin server requires the request to be conditional. - [429 Too Many Requests](https://env.dev/constants#429 Too Many Requests): The user has sent too many requests in a given amount of time (rate limiting). - [431 Request Header Fields Too Large](https://env.dev/constants#431 Request Header Fields Too Large): The server is unwilling to process the request because its header fields are too large. - [451 Unavailable For Legal Reasons](https://env.dev/constants#451 Unavailable For Legal Reasons): The server is denying access to the resource as a consequence of a legal demand. - [500 Internal Server Error](https://env.dev/constants#500 Internal Server Error): The server encountered an unexpected condition that prevented it from fulfilling the request. - [501 Not Implemented](https://env.dev/constants#501 Not Implemented): The server does not support the functionality required to fulfill the request. - [502 Bad Gateway](https://env.dev/constants#502 Bad Gateway): The server, while acting as a gateway or proxy, received an invalid response from an upstream server it accessed in attempting to fulfill the request. - [503 Service Unavailable](https://env.dev/constants#503 Service Unavailable): The server is currently unable to handle the request due to temporary overloading or maintenance. - [504 Gateway Timeout](https://env.dev/constants#504 Gateway Timeout): The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server or some other auxiliary server it needed to access… - [505 HTTP Version Not Supported](https://env.dev/constants#505 HTTP Version Not Supported): The server does not support the major version of HTTP that was used in the request. - [506 Variant Also Negotiates](https://env.dev/constants#506 Variant Also Negotiates): The server has an internal configuration error: the chosen variant resource is configured to engage in transparent content negotiation itself, creating a cir… - [507 Insufficient Storage](https://env.dev/constants#507 Insufficient Storage): The server is unable to store the representation needed to complete the request. - [508 Loop Detected](https://env.dev/constants#508 Loop Detected): The server detected an infinite loop while processing the request. - [510 Not Extended](https://env.dev/constants#510 Not Extended): The policy for accessing the resource has not been met in the request. - [511 Network Authentication Required](https://env.dev/constants#511 Network Authentication Required): The client needs to authenticate to gain network access. - [Apery's constant](https://env.dev/constants#Apery's constant): The value of the Riemann zeta function at 3, denoted zeta(3), approximately 1.20206. - [Avogadro's number](https://env.dev/constants#Avogadro's number): The number of constituent particles in one mole of a substance, exactly 6.02214076 x 10^23 (since 2019 SI redefinition). - [BigInt64Array.BYTES_PER_ELEMENT](https://env.dev/constants#BigInt64Array.BYTES_PER_ELEMENT): The size in bytes of each element in a BigInt64Array, which is 8. - [Boltzmann constant](https://env.dev/constants#Boltzmann constant): Denoted k or kB, exactly 1.380649 x 10^-23 joules per kelvin (since 2019 SI redefinition). - [Boolean.FALSE](https://env.dev/constants#Boolean.FALSE): The Boolean object corresponding to the primitive value false. - [Boolean.TRUE](https://env.dev/constants#Boolean.TRUE): The Boolean object corresponding to the primitive value true. - [Byte.MAX_VALUE](https://env.dev/constants#Byte.MAX_VALUE): The maximum value of a byte: 127 (2^7 - 1). - [Byte.MIN_VALUE](https://env.dev/constants#Byte.MIN_VALUE): The minimum value of a byte: -128 (-2^7). - [Catalan's constant](https://env.dev/constants#Catalan's constant): Denoted G or K, approximately 0.91597. - [Character.MAX_VALUE](https://env.dev/constants#Character.MAX_VALUE): The maximum value of a char: '\uffff' (65535). - [Character.MIN_VALUE](https://env.dev/constants#Character.MIN_VALUE): The minimum value of a char: '\u0000' (0). - [Collections.EMPTY_LIST](https://env.dev/constants#Collections.EMPTY_LIST): An immutable empty List instance. - [Collections.EMPTY_MAP](https://env.dev/constants#Collections.EMPTY_MAP): An immutable empty Map instance. - [Collections.EMPTY_SET](https://env.dev/constants#Collections.EMPTY_SET): An immutable empty Set instance. - [Double.MAX_VALUE](https://env.dev/constants#Double.MAX_VALUE): The largest positive finite value of type double, approximately 1.7976931348623157 × 10^308. - [Double.MIN_VALUE](https://env.dev/constants#Double.MIN_VALUE): The smallest positive nonzero value of type double, approximately 4.9 × 10^-324. - [Double.NaN](https://env.dev/constants#Double.NaN): A constant holding a Not-a-Number value for the double type. - [Double.NEGATIVE_INFINITY](https://env.dev/constants#Double.NEGATIVE_INFINITY): A constant holding negative infinity for the double type. - [Double.POSITIVE_INFINITY](https://env.dev/constants#Double.POSITIVE_INFINITY): A constant holding positive infinity for the double type. - [E (Euler's number)](https://env.dev/constants#E (Euler's number)): The base of the natural logarithm, approximately 2.71828. - [Elementary charge](https://env.dev/constants#Elementary charge): The electric charge carried by a single proton, denoted e, exactly 1.602176634 x 10^-19 coulombs (since 2019 SI redefinition). - [Ellipsis](https://env.dev/constants#Ellipsis): A special singleton value, also accessible as the literal '...'. - [Euler-Mascheroni constant](https://env.dev/constants#Euler-Mascheroni constant): Denoted by gamma, approximately 0.57722. - [False](https://env.dev/constants#False): The boolean false value in Python, an instance of int with value 0. - [Fine-structure constant](https://env.dev/constants#Fine-structure constant): Denoted alpha, approximately 1/137.036. - [Float.MAX_VALUE](https://env.dev/constants#Float.MAX_VALUE): The largest positive finite value of type float, approximately 3.4028235 × 10^38. - [Float.MIN_VALUE](https://env.dev/constants#Float.MIN_VALUE): The smallest positive nonzero value of type float, approximately 1.4 × 10^-45. - [Float.NaN](https://env.dev/constants#Float.NaN): A constant holding a Not-a-Number value for the float type. - [Float.NEGATIVE_INFINITY](https://env.dev/constants#Float.NEGATIVE_INFINITY): A constant holding negative infinity for the float type. - [Float.POSITIVE_INFINITY](https://env.dev/constants#Float.POSITIVE_INFINITY): A constant holding positive infinity for the float type. - [float('-inf')](https://env.dev/constants#float('-inf')): Creates a negative infinity float value. - [float('inf')](https://env.dev/constants#float('inf')): Creates a positive infinity float value. - [float('nan')](https://env.dev/constants#float('nan')): Creates a Not-a-Number float value. - [Float32Array.BYTES_PER_ELEMENT](https://env.dev/constants#Float32Array.BYTES_PER_ELEMENT): The size in bytes of each element in a Float32Array, which is 4. - [Float64Array.BYTES_PER_ELEMENT](https://env.dev/constants#Float64Array.BYTES_PER_ELEMENT): The size in bytes of each element in a Float64Array, which is 8. - [globalThis](https://env.dev/constants#globalThis): A global property that provides a standard way to access the global this value across environments. - [Golden Ratio (Phi)](https://env.dev/constants#Golden Ratio (Phi)): Equal to (1 + sqrt(5)) / 2, approximately 1.61803. - [Gravitational constant](https://env.dev/constants#Gravitational constant): Denoted G, approximately 6.674 x 10^-11 N·m^2/kg^2. - [Infinity](https://env.dev/constants#Infinity): A global property representing positive infinity. - [Int16Array.BYTES_PER_ELEMENT](https://env.dev/constants#Int16Array.BYTES_PER_ELEMENT): The size in bytes of each element in an Int16Array, which is 2. - [Int32Array.BYTES_PER_ELEMENT](https://env.dev/constants#Int32Array.BYTES_PER_ELEMENT): The size in bytes of each element in an Int32Array, which is 4. - [Int8Array.BYTES_PER_ELEMENT](https://env.dev/constants#Int8Array.BYTES_PER_ELEMENT): The size in bytes of each element in an Int8Array, which is 1. - [Integer.MAX_VALUE](https://env.dev/constants#Integer.MAX_VALUE): The maximum value of a 32-bit signed integer: 2^31 - 1. - [Integer.MIN_VALUE](https://env.dev/constants#Integer.MIN_VALUE): The minimum value of a 32-bit signed integer: -2^31. - [io.SeekCurrent](https://env.dev/constants#io.SeekCurrent): Seek relative to the current offset in the file. - [io.SeekEnd](https://env.dev/constants#io.SeekEnd): Seek relative to the end of the file. - [io.SeekStart](https://env.dev/constants#io.SeekStart): Seek relative to the origin (beginning) of the file. - [Ln(2)](https://env.dev/constants#Ln(2)): The natural logarithm of 2, approximately 0.69315. - [Long.MAX_VALUE](https://env.dev/constants#Long.MAX_VALUE): The maximum value of a 64-bit signed integer: 2^63 - 1. - [Long.MIN_VALUE](https://env.dev/constants#Long.MIN_VALUE): The minimum value of a 64-bit signed integer: -2^63. - [math.e](https://env.dev/constants#math.e): Euler's number, the base of natural logarithms, approximately 2.71828. - [math.E](https://env.dev/constants#math.E): Euler's number, the base of natural logarithms, approximately 2.71828. - [Math.E](https://env.dev/constants#Math.E): Euler's number, the base of natural logarithms, approximately 2.71828. - [Math.E](https://env.dev/constants#Math.E): Euler's number (e), the base of natural logarithms. - [math.inf](https://env.dev/constants#math.inf): A floating-point positive infinity. - [math.Ln10](https://env.dev/constants#math.Ln10): The natural logarithm of 10, approximately 2.30259. - [Math.LN10](https://env.dev/constants#Math.LN10): The natural logarithm of 10, approximately 2.302. - [math.Ln2](https://env.dev/constants#math.Ln2): The natural logarithm of 2, approximately 0.69315. - [Math.LN2](https://env.dev/constants#Math.LN2): The natural logarithm of 2, approximately 0.693. - [math.Log10E](https://env.dev/constants#math.Log10E): The base-10 logarithm of Euler's number (e), approximately 0.43429. - [Math.LOG10E](https://env.dev/constants#Math.LOG10E): The base-10 logarithm of Euler's number (e), approximately 0.434. - [math.Log2E](https://env.dev/constants#math.Log2E): The base-2 logarithm of Euler's number (e), approximately 1.44269. - [Math.LOG2E](https://env.dev/constants#Math.LOG2E): The base-2 logarithm of Euler's number (e), approximately 1.442. - [math.MaxFloat32](https://env.dev/constants#math.MaxFloat32): The largest finite value representable by a float32, approximately 3.4028 × 10^38. - [math.MaxFloat64](https://env.dev/constants#math.MaxFloat64): The largest finite value representable by a float64, approximately 1.7977 × 10^308. - [math.MaxInt](https://env.dev/constants#math.MaxInt): The maximum value of an int, which is platform-dependent. - [math.MaxInt64](https://env.dev/constants#math.MaxInt64): The maximum value of an int64: 2^63 - 1. - [math.MaxUint](https://env.dev/constants#math.MaxUint): The maximum value of a uint, which is platform-dependent. - [math.MinInt](https://env.dev/constants#math.MinInt): The minimum value of an int, which is platform-dependent. - [math.MinInt64](https://env.dev/constants#math.MinInt64): The minimum value of an int64: -2^63. - [math.nan](https://env.dev/constants#math.nan): A floating-point Not-a-Number value. - [math.Phi](https://env.dev/constants#math.Phi): The golden ratio, approximately 1.61803. - [math.pi](https://env.dev/constants#math.pi): The mathematical constant pi, the ratio of a circle's circumference to its diameter, approximately 3.14159. - [math.Pi](https://env.dev/constants#math.Pi): The mathematical constant pi, the ratio of a circle's circumference to its diameter. - [Math.PI](https://env.dev/constants#Math.PI): The ratio of a circle's circumference to its diameter, approximately 3.14159. - [Math.PI](https://env.dev/constants#Math.PI): The ratio of the circumference of a circle to its diameter, defined as the double value closest to pi. - [math.SmallestNonzeroFloat32](https://env.dev/constants#math.SmallestNonzeroFloat32): The smallest positive non-zero value representable by a float32, approximately 1.401 × 10^-45. - [math.SmallestNonzeroFloat64](https://env.dev/constants#math.SmallestNonzeroFloat64): The smallest positive non-zero value representable by a float64, approximately 5 × 10^-324. - [Math.SQRT1_2](https://env.dev/constants#Math.SQRT1_2): The square root of 1/2, approximately 0.707. - [math.Sqrt2](https://env.dev/constants#math.Sqrt2): The square root of 2, approximately 1.41421. - [Math.SQRT2](https://env.dev/constants#Math.SQRT2): The square root of 2, approximately 1.414. - [math.SqrtE](https://env.dev/constants#math.SqrtE): The square root of Euler's number (e), approximately 1.64872. - [math.SqrtPhi](https://env.dev/constants#math.SqrtPhi): The square root of the golden ratio (phi), approximately 1.27202. - [math.SqrtPi](https://env.dev/constants#math.SqrtPi): The square root of pi, approximately 1.77245. - [math.tau](https://env.dev/constants#math.tau): The mathematical constant tau, equal to 2*pi (approximately 6.28318). - [NaN](https://env.dev/constants#NaN): A global property representing Not-a-Number. - [None](https://env.dev/constants#None): The sole value of the NoneType, used to represent the absence of a value. - [NotImplemented](https://env.dev/constants#NotImplemented): A special singleton value that should be returned by binary special methods (e.g. - [null](https://env.dev/constants#null): A primitive value representing the intentional absence of any object value. - [Number.EPSILON](https://env.dev/constants#Number.EPSILON): The difference between 1 and the smallest floating-point number greater than 1, approximately 2.220446049250313 × 10^-16. - [Number.MAX_SAFE_INTEGER](https://env.dev/constants#Number.MAX_SAFE_INTEGER): The maximum safe integer in JavaScript, equal to 2^53 - 1. - [Number.MAX_VALUE](https://env.dev/constants#Number.MAX_VALUE): The largest positive finite number representable in JavaScript, approximately 1.7976931348623157 × 10^308. - [Number.MIN_SAFE_INTEGER](https://env.dev/constants#Number.MIN_SAFE_INTEGER): The minimum safe integer in JavaScript, equal to -(2^53 - 1). - [Number.MIN_VALUE](https://env.dev/constants#Number.MIN_VALUE): The smallest positive number representable in JavaScript, approximately 5 × 10^-324. - [Number.NaN](https://env.dev/constants#Number.NaN): Represents Not-a-Number. - [Number.NEGATIVE_INFINITY](https://env.dev/constants#Number.NEGATIVE_INFINITY): Represents negative infinity. - [Number.POSITIVE_INFINITY](https://env.dev/constants#Number.POSITIVE_INFINITY): Represents positive infinity. - [os.curdir](https://env.dev/constants#os.curdir): The constant string used by the OS to refer to the current directory. - [os.devnull](https://env.dev/constants#os.devnull): The file path of the null device. - [os.linesep](https://env.dev/constants#os.linesep): The string used to separate lines on the current platform. - [os.pardir](https://env.dev/constants#os.pardir): The constant string used by the OS to refer to the parent directory. - [os.PathListSeparator](https://env.dev/constants#os.PathListSeparator): The OS-specific path list separator character. - [os.pathsep](https://env.dev/constants#os.pathsep): The character conventionally used to separate search path components, such as in PATH. - [os.PathSeparator](https://env.dev/constants#os.PathSeparator): The OS-specific path separator character. - [os.sep](https://env.dev/constants#os.sep): The character used by the operating system to separate pathname components. - [Pi](https://env.dev/constants#Pi): The ratio of a circle's circumference to its diameter, one of the most fundamental and widely recognized mathematical constants. - [Planck's constant](https://env.dev/constants#Planck's constant): A fundamental physical constant denoted h, equal to exactly 6.62607015 x 10^-34 joule-seconds (since 2019 SI redefinition). - [RegExp.lastMatch](https://env.dev/constants#RegExp.lastMatch): A static property that returns the last matched substring. - [Short.MAX_VALUE](https://env.dev/constants#Short.MAX_VALUE): The maximum value of a 16-bit signed integer: 2^15 - 1. - [Short.MIN_VALUE](https://env.dev/constants#Short.MIN_VALUE): The minimum value of a 16-bit signed integer: -2^15. - [Speed of light](https://env.dev/constants#Speed of light): The speed of light in vacuum, denoted c, is exactly 299,792,458 meters per second. - [Sqrt(2)](https://env.dev/constants#Sqrt(2)): The square root of 2, approximately 1.41421. - [std::char::MAX](https://env.dev/constants#std::char::MAX): The highest valid Unicode code point, U+10FFFF (1114111 in decimal). - [std::f64::consts::E](https://env.dev/constants#std::f64::consts::E): Euler's number, the base of natural logarithms, approximately 2.71828. - [std::f64::consts::FRAC_PI_2](https://env.dev/constants#std::f64::consts::FRAC_PI_2): Pi divided by 2 (pi/2), approximately 1.5708. - [std::f64::consts::FRAC_PI_4](https://env.dev/constants#std::f64::consts::FRAC_PI_4): Pi divided by 4 (pi/4), approximately 0.7854. - [std::f64::consts::LN_10](https://env.dev/constants#std::f64::consts::LN_10): The natural logarithm of 10, approximately 2.30259. - [std::f64::consts::LN_2](https://env.dev/constants#std::f64::consts::LN_2): The natural logarithm of 2, approximately 0.69315. - [std::f64::consts::LOG10_E](https://env.dev/constants#std::f64::consts::LOG10_E): The base-10 logarithm of Euler's number (e), approximately 0.43429. - [std::f64::consts::LOG2_E](https://env.dev/constants#std::f64::consts::LOG2_E): The base-2 logarithm of Euler's number (e), approximately 1.44269. - [std::f64::consts::PI](https://env.dev/constants#std::f64::consts::PI): The ratio of a circle's circumference to its diameter (pi). - [std::f64::consts::SQRT_2](https://env.dev/constants#std::f64::consts::SQRT_2): The square root of 2, approximately 1.41421. - [std::f64::consts::TAU](https://env.dev/constants#std::f64::consts::TAU): The full circle constant (tau), equal to 2*pi, approximately 6.28318. - [std::f64::EPSILON](https://env.dev/constants#std::f64::EPSILON): The machine epsilon for f64, approximately 2.2204 × 10^-16. - [std::f64::INFINITY](https://env.dev/constants#std::f64::INFINITY): Positive infinity for f64. - [std::f64::MAX](https://env.dev/constants#std::f64::MAX): The largest finite f64 value, approximately 1.7977 × 10^308. - [std::f64::MIN](https://env.dev/constants#std::f64::MIN): The smallest finite f64 value (most negative), approximately -1.7977 × 10^308. - [std::f64::NAN](https://env.dev/constants#std::f64::NAN): Not-a-Number for f64. - [std::f64::NEG_INFINITY](https://env.dev/constants#std::f64::NEG_INFINITY): Negative infinity for f64. - [std::i32::MAX](https://env.dev/constants#std::i32::MAX): The maximum value of a 32-bit signed integer: 2^31 - 1. - [std::i32::MIN](https://env.dev/constants#std::i32::MIN): The minimum value of a 32-bit signed integer: -2^31. - [std::u8::MAX](https://env.dev/constants#std::u8::MAX): The maximum value of an unsigned 8-bit integer: 255 (2^8 - 1). - [std::usize::MAX](https://env.dev/constants#std::usize::MAX): The maximum value of a usize, which is platform-dependent. - [std::usize::MIN](https://env.dev/constants#std::usize::MIN): The minimum value of a usize, always 0. - [string.ascii_letters](https://env.dev/constants#string.ascii_letters): A string containing all ASCII letters, both lowercase and uppercase. - [string.ascii_lowercase](https://env.dev/constants#string.ascii_lowercase): A string containing all lowercase ASCII letters: 'abcdefghijklmnopqrstuvwxyz'. - [string.ascii_uppercase](https://env.dev/constants#string.ascii_uppercase): A string containing all uppercase ASCII letters: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'. - [string.digits](https://env.dev/constants#string.digits): A string containing all decimal digit characters: '0123456789'. - [string.hexdigits](https://env.dev/constants#string.hexdigits): A string containing all hexadecimal digit characters: '0123456789abcdefABCDEF'. - [string.octdigits](https://env.dev/constants#string.octdigits): A string containing all octal digit characters: '01234567'. - [string.punctuation](https://env.dev/constants#string.punctuation): A string containing all ASCII punctuation characters: !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~. - [string.whitespace](https://env.dev/constants#string.whitespace): A string containing all ASCII whitespace characters: space, tab, newline, carriage return, vertical tab, and form feed. - [Symbol.asyncIterator](https://env.dev/constants#Symbol.asyncIterator): A well-known symbol that specifies the default async iterator for an object. - [Symbol.hasInstance](https://env.dev/constants#Symbol.hasInstance): A well-known symbol used to determine if a constructor object recognizes an object as its instance. - [Symbol.iterator](https://env.dev/constants#Symbol.iterator): A well-known symbol that specifies the default iterator for an object. - [Symbol.match](https://env.dev/constants#Symbol.match): A well-known symbol that specifies the matching of a regular expression against a string. - [Symbol.replace](https://env.dev/constants#Symbol.replace): A well-known symbol that specifies the method called by String.prototype.replace() to replace matched substrings. - [Symbol.search](https://env.dev/constants#Symbol.search): A well-known symbol that specifies the method called by String.prototype.search() to return the index within a string that matches a pattern. - [Symbol.species](https://env.dev/constants#Symbol.species): A well-known symbol that specifies the constructor function used to create derived objects. - [Symbol.split](https://env.dev/constants#Symbol.split): A well-known symbol that specifies the method called by String.prototype.split() to split a string at the indices that match a pattern. - [Symbol.toPrimitive](https://env.dev/constants#Symbol.toPrimitive): A well-known symbol that specifies a method to convert an object to a primitive value. - [Symbol.toStringTag](https://env.dev/constants#Symbol.toStringTag): A well-known symbol used to create the default string description of an object. - [sys.float_info.epsilon](https://env.dev/constants#sys.float_info.epsilon): The smallest float such that 1.0 + epsilon != 1.0, approximately 2.220446049250313 × 10^-16. - [sys.float_info.max](https://env.dev/constants#sys.float_info.max): The maximum representable positive finite float, approximately 1.7976931348623157 × 10^308. - [sys.float_info.min](https://env.dev/constants#sys.float_info.min): The minimum positive normalized float, approximately 2.2250738585072014 × 10^-308. - [sys.maxsize](https://env.dev/constants#sys.maxsize): The largest positive integer supported by the platform's Py_ssize_t type. - [Tau](https://env.dev/constants#Tau): The circle constant equal to 2*pi, approximately 6.28318. - [True](https://env.dev/constants#True): The boolean true value in Python, an instance of int with value 1. - [Uint16Array.BYTES_PER_ELEMENT](https://env.dev/constants#Uint16Array.BYTES_PER_ELEMENT): The size in bytes of each element in a Uint16Array, which is 2. - [Uint32Array.BYTES_PER_ELEMENT](https://env.dev/constants#Uint32Array.BYTES_PER_ELEMENT): The size in bytes of each element in a Uint32Array, which is 4. - [Uint8Array.BYTES_PER_ELEMENT](https://env.dev/constants#Uint8Array.BYTES_PER_ELEMENT): The size in bytes of each element in a Uint8Array, which is 1. - [undefined](https://env.dev/constants#undefined): A primitive value automatically assigned to variables that have been declared but not initialized. ## Optional ## References - [Environment Variables Reference](https://env.dev/variables): 244 environment variables across AWS, Azure, Docker, Node.js and more. - [Programming Constants Reference](https://env.dev/constants): 222 constants across JavaScript, Python, Go, Rust and more.