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Free developer tools, guides, and references — all client-side, no signup required.
Looking for .env? Read the complete guide to environment variable files.
Developer Tools
Browse all →JSON Formatter & Validator
Prettify and validate instantly
Base64 Encode / Decode
Encode and decode text, URLs and files
IP Subnet Calculator
CIDR to IP range with visual breakdown
JWT Debugger
Decode, inspect and verify tokens
Client-side utilities — JSON formatter, Base64 encoder, UUID generator, and more.
Popular Comparisons
View all 10 comparisons →Comparison
REST vs GraphQL: Which API Style Should You Use?
Compare REST and GraphQL APIs side by side. Understand the trade-offs in performance, flexibility, caching, and developer experience to choose the right approach.
Comparison
Docker vs Kubernetes: What's the Difference?
Understand the difference between Docker and Kubernetes. Docker builds and runs containers; Kubernetes orchestrates them at scale. Learn when to use each.
Comparison
npm vs yarn vs pnpm: Package Manager Comparison
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.
Comparison
PostgreSQL vs MySQL: Which Database to Choose?
Compare PostgreSQL and MySQL databases. Analyze performance, features, JSON support, replication, and ecosystem to choose the right database for your project.
Comparison
Redis vs Memcached: In-Memory Caching Compared
Compare Redis and Memcached for caching. Evaluate data structures, persistence, clustering, and use cases to pick the right in-memory store.
Comparison
Nginx vs Apache: Web Server Comparison
Compare Nginx and Apache web servers. Evaluate performance, configuration, modules, reverse proxy capabilities, and resource usage.
References
Environment Variables
100+ environment variables across AWS, Azure, Docker, Node.js and more — with best practices and a .env validator.
Browse variables →Programming Constants
Essential constants across JavaScript, Python, Go, Rust and more — values, types, and best practices.
Browse constants →Everything starts with env
Cursor
AI-native code editor built on VS Code. Features inline LLM editing, chat, and multi-file agentic coding.
Windsurf
AI-powered IDE by Codeium with Cascade, an agentic LLM coding assistant that understands your full codebase.
GitHub Copilot
AI pair programmer by GitHub. LLM-powered autocomplete, chat, and agent mode integrated into VS Code and JetBrains.
Claude Code
Anthropic's CLI-based agentic LLM coding tool. Terminal-first AI assistant for complex multi-file tasks.
Codeium
Free AI code completion tool. Fast LLM-powered autocomplete for 70+ languages across all major editors.
MCP Servers
Browse all →mckinsey/vizro-mcp
Create validated data charts and dashboards.
supabase-community/supabase-mcp
Official Supabase MCP server for AI integration.
zcaceres/markdownify-mcp
Convert files to Markdown.
datalayer/jupyter-mcp-server
MCP Server for Jupyter.
xing5/mcp-google-sheets
Google Sheets API interaction MCP server.
AI Coding Skills
Browse all →Algorithmic Art
Create algorithmic art using p5.js with seeded randomness and interactive parameter exploration.
Brand Guidelines
Apply Anthropic's official brand colors and typography to any artifact.
Canvas Design
Create beautiful visual art in .png and .pdf documents using design philosophy.
Doc Coauthoring
Guide users through a structured workflow for co-authoring documentation.
DOCX
Create, read, edit, or manipulate Word documents (.docx files).
Discounts
Browse all →AWS Activate
Up to $100k in AWS credits for startups. Apply through the AWS Activate program with your startup details.
$2k+ creditsGoogle Cloud for Startups
Over $2,000 in Google Cloud credits for eligible startups. Apply through the Google for Startups program.
$150k creditsMicrosoft for Startups (Azure)
Up to $150k in Azure credits plus free access to Microsoft tools. Apply through the Microsoft for Startups Founders Hub.
$200 creditsDigitalOcean Hatch
$200 in infrastructure credits for startups. Apply through the Hatch startup program with your company details.
Free tierCloudflare
Generous free tier including CDN, DNS, DDoS protection, and Workers. Available to everyone, just sign up.
Latest Guides
View all 48 guides →Next.js Environment Variables: Complete Guide
How Next.js handles environment variables: .env files, NEXT_PUBLIC_ prefix, server vs client access, load order, and common production errors.
GitHub Actions: Secrets vs Environment Variables
When to use repository secrets, environment secrets, and configuration variables in GitHub Actions. Includes workflow examples for Node.js, Python, and Docker.
Node.js Environment Variables: process.env, dotenv & --env-file
How to use environment variables in Node.js. Covers process.env, dotenv, Node 20.6+ --env-file flag, NODE_ENV, type-safe validation with zod, and cross-platform support.
Environment Variables Security: Secrets, Leaks & Best Practices
Why environment variables are not truly secure and what to do about it. Covers secret rotation, leak detection, client-side exposure risks, and when to use a dedicated secrets manager.
Go Environment Variables: os.Getenv, godotenv & Viper
How to read, set, and manage environment variables in Go. Covers os.Getenv, os.LookupEnv, godotenv, Viper, envconfig, build-time variables, and testing.
JWT Security Best Practices: Token Storage, Algorithms & Revocation
Security best practices for JSON Web Tokens: algorithm selection, token storage, expiration, refresh patterns, revocation strategies, and common vulnerabilities to avoid.
Cheatsheets
View all 31 cheatsheets →HTTP Status Codes — Complete Quick Reference
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
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
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
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
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
Quick reference for Nginx: service management, server blocks, reverse proxy, load balancing, SSL/TLS, location matching, logging, and performance tuning.
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