Overview
GitHub Copilot Extensions let third-party tools integrate directly into the Copilot Chat experience. Instead of switching between tools, you can query databases, trigger deployments, search documentation, and more — all from within Copilot Chat using @mentions of installed extensions. This turns Copilot from a code completion tool into a full development platform powered by LLMs.
Popular Extensions
@docker
Get help with Dockerfiles, docker-compose, container optimization, and debugging container issues.
@sentry
Query Sentry for error details, stack traces, and fix suggestions directly in your editor.
@azure
Manage Azure resources, deploy applications, and get cloud architecture guidance.
Building a Custom Extension
- •Create a GitHub App with the Copilot Agent permission
- •Implement an HTTP endpoint that receives chat messages
- •Return responses using the Copilot Extensions API format
- •Add context from your domain — database schemas, API docs, internal tools
- •Publish privately for your org or publicly on the marketplace
Custom Instructions
.github/copilot-instructions.md
# Project Instructions for Copilot
## Tech Stack
- TypeScript, React 19, Tailwind CSS v4
- API: tRPC with Zod validation
- Database: PostgreSQL via Drizzle ORM
## Conventions
- Use named exports, not default exports
- Prefer server components in Next.js
- All database queries go through the repository pattern
- Use Result types for error handling, not exceptions