Copilot API Proxy (Fork)

Note

This is a fork of ericc-ch/copilot-api with additional improvements and bug fixes.

Warning

This is a reverse proxy for the GitHub Copilot API. It is not officially supported by GitHub and may break at any time. Use at your own risk.

A reverse proxy that exposes GitHub Copilot's API as standard OpenAI and Anthropic compatible endpoints. Works with Claude Code, Cursor, and other tools that speak these protocols.

Quick Start

Install from npm (Recommended)

npx -y @hsupu/copilot-api start

Run from Source

git clone https://github.com/puxu-msft/copilot-api-js.git
cd copilot-api-js
bun install
bun run dev      # Development mode with hot reload
bun run start    # Production mode
bun run build    # Build for distribution

# Testing
bun test                   # Backend unit tests
bun run test:all           # All backend tests
bun run test:ui            # Frontend (History UI) tests
bun run typecheck          # TypeScript type checking

Using with Claude Code

Run the interactive setup command:

copilot-api setup-claude-code

Or manually create ~/.claude/settings.json:

{
  "env": {
    "ANTHROPIC_BASE_URL": "http://localhost:4141",
    "ANTHROPIC_AUTH_TOKEN": "dummy",
    "ANTHROPIC_MODEL": "opus",
    "ANTHROPIC_SMALL_FAST_MODEL": "haiku",
    "DISABLE_NON_ESSENTIAL_MODEL_CALLS": "1",
    "CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC": "1"
  }
}

Features

Dual API Compatibility

Exposes both OpenAI and Anthropic compatible endpoints through a single proxy:

• Direct Anthropic path — Uses Copilot API's native Anthropic endpoint for Claude models
• OpenAI-compatible path — Forwards OpenAI Chat Completions, Responses, Embeddings, and Models requests to Copilot's OpenAI endpoints

Auto-Truncate

Automatically handles context length limits (enabled by default):

• Reactive — Retries failed requests with a truncated payload when hitting token or byte limits
• Proactive — Pre-checks requests against known model limits before sending
• Dynamic limit learning — Adjusts limits based on actual API error responses
• Tool result compression — Compresses old tool_result content before truncating messages

Message Sanitization

Cleans up messages before forwarding to the API:

• Filters orphaned tool_use / tool_result blocks (unpaired due to interrupted tool calls or truncation)
• Fixes tool name casing mismatches
• Removes empty text content blocks
• Strips <system-reminder> tags from message content
• [Optional] Deduplicates repeated tool calls (config.yaml: anthropic.dedup_tool_calls)
• [Optional] Strips system-reminder tags from Read tool results (config.yaml: anthropic.truncate_read_tool_result)

Model Name Translation

Translates client-sent model names to matching Copilot models:

Input	Resolved To
opus, sonnet, haiku	Best available model in that family
claude-opus-4-6	claude-opus-4.6
claude-sonnet-4-6-20250514	claude-sonnet-4.6
claude-opus-4-6-fast, opus[1m]	claude-opus-4.6-fast, claude-opus-4.6-1m
claude-sonnet-4, gpt-4	Passed through directly

User-configured model_overrides (via config.yaml) can redirect any model name to another, with chained resolution and family-level overrides.

Server-Side Tools

Supports Anthropic server-side tools (web_search, tool_search). These tools are executed by the API backend, with both server_tool_use and result blocks appearing inline in assistant messages. Tool definitions can optionally be rewritten to a custom format (--no-rewrite-anthropic-tools).

Request History UI

Built-in web interface for inspecting API requests and responses. Access at http://localhost:4141/history/v3/.

• Real-time updates via WebSocket
• Filter by model, endpoint, status, and time range
• Session tracking and statistics

Additional Features

• Model overrides — Configure arbitrary model name redirections via config.yaml
• Adaptive rate limiting — Intelligent rate limiting with exponential backoff (3 modes: Normal, Rate-limited, Recovering)
• Tool name truncation — Truncates tool names exceeding 64 characters (OpenAI limit) with hash suffixes
• Health checks — Container-ready endpoint at /health
• Graceful shutdown — Connection draining on shutdown signals
• Proxy support — HTTP/HTTPS proxy via environment variables

Commands

Command	Description
start	Start the API server (authenticates automatically if needed)
auth	Run GitHub authentication flow only
logout	Remove stored GitHub token
check-usage	Show Copilot usage and quota information
debug info	Display diagnostic information
debug models	Fetch and display raw model data from Copilot API
list-claude-code	List all locally installed Claude Code versions
setup-claude-code	Interactively configure Claude Code to use this proxy

start Options

General:

Option	Default	Description
--port, -p	4141	Port to listen on
--host, -H	(all interfaces)	Host/interface to bind to
--verbose, -v	false	Enable verbose logging
--account-type, -a	individual	Account type: individual, business, or enterprise
--github-token, -g		Provide GitHub token directly
--no-http-proxy-from-env	enabled	Disable HTTP proxy from environment variables

Auto-Truncate:

Option	Default	Description
--no-auto-truncate	enabled	Disable auto-truncation on context limit errors

Anthropic-Specific (via config.yaml):

These options are configured in config.yaml under the anthropic: section. See config.example.yaml.

Config Key	Default	Description
anthropic.rewrite_tools	true	Rewrite server-side tools to custom format
stream_idle_timeout	300	Max seconds between SSE events (0 = no timeout)

Sanitization:

Option	Default	Description
--collect-system-prompts	false	Collect system prompts to file

Rate Limiting:

Option	Default	Description
--no-rate-limit	enabled	Disable adaptive rate limiting

Rate limiter sub-parameters are configured in config.yaml under rate_limiter:. See config.example.yaml.

Configuration

Create a config.yaml in the working directory. See config.example.yaml for all available options.

API Endpoints

OpenAI Compatible

Endpoint	Method	Description
/v1/chat/completions	POST	Chat completions
/v1/responses	POST	Responses API
/v1/models	GET	List available models
/v1/models/:model	GET	Get specific model details
/v1/embeddings	POST	Text embeddings

All endpoints also work without the /v1 prefix.

Anthropic Compatible

Endpoint	Method	Description
/v1/messages	POST	Messages API
/v1/messages/count_tokens	POST	Token counting

Utility

Endpoint	Method	Description
/health	GET	Health check (200 healthy, 503 unhealthy)
/usage	GET	Copilot usage and quota statistics
/token	GET	Current Copilot token information
/history/v3/	GET	History web UI
/history/ws	WebSocket	Real-time history updates
/history/api/entries	GET	Query history entries
/history/api/entries/:id	GET	Get single entry
/history/api/summaries	GET	Entry summaries
/history/api/stats	GET	Usage statistics
/history/api/sessions	GET	List sessions

Account Types

The account type determines the Copilot API base URL:

Type	API Base URL
individual	api.githubcopilot.com
business	api.business.githubcopilot.com
enterprise	api.enterprise.githubcopilot.com

License

MIT