copilot2api

A lightweight Go proxy that exposes GitHub Copilot as both OpenAI-compatible and Anthropic-compatible API endpoints.

Features

• OpenAI API Compatible: /v1/chat/completions, /v1/models, /v1/embeddings, /v1/responses
• Anthropic API Compatible: /v1/messages
• Streaming Support: Full SSE streaming for both OpenAI and Anthropic formats
• Anthropic Routing: Uses native /v1/messages when the model supports it, otherwise routes via /responses or /chat/completions
• Auto Authentication: GitHub Device Flow OAuth with automatic token refresh
• Usage Monitoring: Built-in /usage endpoint for quota tracking
• Models Cache: 5-minute cache for /v1/models and Anthropic model capability lookups

Quick Start

# Build from source (requires Go 1.26+)
go build -o copilot2api .

# Start the proxy
./copilot2api

First run will prompt GitHub Device Flow authentication:

🔐 GitHub Authentication Required
Please visit: https://github.com/login/device
Enter code: XXXX-XXXX

Waiting for authorization...
✅ Authentication successful!

Server starts on http://127.0.0.1:7777 by default.

Security

⚠️ This proxy is designed for local development only.

• Does not implement API key validation — any request is accepted
• Do not expose publicly — it becomes an open proxy consuming your Copilot quota
• Credentials are stored in ~/.config/copilot2api/credentials.json

Usage with Claude Code

Add to ~/.claude/settings.json:

{
  "env": {
    "ANTHROPIC_BASE_URL": "http://127.0.0.1:7777",
    "ANTHROPIC_API_KEY": "dummy",
    "ANTHROPIC_MODEL": "claude-opus-4.6",
    "ANTHROPIC_SMALL_FAST_MODEL": "claude-haiku-4.5",
    "CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC": "1"
  },
  "permissions": {
    "deny": [
      "WebSearch"
    ]
  }
}

1M Context Window

copilot2api supports Claude 1M context models. When Claude Code sends the anthropic-beta: context-1m-... header, the proxy automatically appends -1m to the model ID (e.g. claude-opus-4.6 → claude-opus-4.6-1m) so Copilot routes to the 1M variant.

To use it, select the 1M model variant in Claude Code via the /model command (e.g. Opus (1M)). Without this, Claude Code defaults to the standard 200K context window.

Usage with Codex

Add to ~/.codex/config.toml:

model = "gpt-5.3-codex"
model_provider = "copilot2api"
model_reasoning_effort = "high"
web_search = "disabled"

[model_providers.copilot2api]
name = "copilot2api"
base_url = "http://127.0.0.1:7777/v1"
wire_api = "responses"
api_key = "dummy"

Usage with curl

# OpenAI chat completion
curl http://localhost:7777/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{"model":"gpt-5.3-codex","messages":[{"role":"user","content":"Hello!"}]}'

# Anthropic message
curl http://localhost:7777/v1/messages \
  -H "Content-Type: application/json" \
  -H "x-api-key: dummy" \
  -d '{"model":"claude-sonnet-4.6","messages":[{"role":"user","content":"Hello!"}],"max_tokens":100}'

# List models
curl http://localhost:7777/v1/models

# Check usage/quota
curl http://localhost:7777/usage

Usage with SDKs

OpenAI Python SDK

import openai

client = openai.OpenAI(
    api_key="dummy",
    base_url="http://127.0.0.1:7777/v1"
)

response = client.chat.completions.create(
    model="gpt-5.3-codex",
    messages=[{"role": "user", "content": "Hello!"}]
)

Anthropic Python SDK

import anthropic

client = anthropic.Anthropic(
    api_key="dummy",
    base_url="http://127.0.0.1:7777"
)

message = client.messages.create(
    model="claude-sonnet-4.6",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}]
)

API Endpoints

Endpoint	Method	Description
/v1/chat/completions	POST	OpenAI Chat Completions (streaming & non-streaming)
/v1/responses	POST	OpenAI Responses API
/v1/models	GET	List available models (5min cache)
/v1/embeddings	POST	Generate embeddings (string or array input)
/v1/messages	POST	Anthropic Messages API (streaming & non-streaming)
/usage	GET	Copilot usage and quota info

Configuration

CLI Flags

./copilot2api [options]

  -host string       Server host (default "127.0.0.1")
  -port int          Server port (default 7777)
  -token-dir string  Token storage directory (default ~/.config/copilot2api)
  -debug             Enable debug logging
  -version           Show version and exit

Environment Variables

Environment variables are used as defaults when flags are not provided:

Variable	Description	Default
COPILOT2API_HOST	Server host	127.0.0.1
COPILOT2API_PORT	Server port	7777
COPILOT2API_TOKEN_DIR	Token storage directory	~/.config/copilot2api
COPILOT2API_DEBUG	Enable debug logging (true/false, 1/0)	false

CLI flags take precedence over environment variables.

Docker

docker run -it -p 7777:7777 \
  -v ~/.config/copilot2api:/root/.config/copilot2api \
  ghcr.io/whtsky/copilot2api

The Docker image defaults to COPILOT2API_HOST=0.0.0.0 so port forwarding works out of the box. The volume mount persists your GitHub credentials across container restarts. First run will prompt Device Flow authentication.

To use a custom port:

docker run -it -p 8080:8080 \
  -v ~/.config/copilot2api:/root/.config/copilot2api \
  -e COPILOT2API_PORT=8080 \
  ghcr.io/whtsky/copilot2api

⚠️ The Docker image listens on all interfaces by default. Only publish the port to 127.0.0.1 (e.g. -p 127.0.0.1:7777:7777) unless you know what you're doing.

How It Works

1. Authenticates with GitHub via Device Flow OAuth
2. Exchanges GitHub token for Copilot API token (auto-refreshes)
3. Proxies OpenAI-format requests directly to Copilot API
4. Routes Anthropic Messages requests by model capabilities (native /v1/messages, translated /responses, or translated /chat/completions)
5. Automatically detects API endpoint from token (Individual/Business/Enterprise)

Development

go test ./...              # Run tests
go build -o copilot2api .  # Build

License

MIT