copillm

A local proxy that brings Claude Code, Codex CLI, and other coding agents to your existing GitHub Copilot subscription.

What is copillm?

copillm is a local daemon that exposes OpenAI-compatible and Anthropic-compatible HTTP endpoints, backed by your existing GitHub Copilot subscription.

Any tool that speaks the OpenAI Chat Completions or Anthropic Messages wire format — Claude Code, Codex CLI, OpenAI SDK scripts, your own bots — can run against your Copilot seat without managing additional API keys.

Getting started

npm install -g copillm   # or use `npx copillm ...` below

copillm auth login   # one-time GitHub device-flow login
copillm claude       # launches Claude Code, fully wired
copillm codex        # launches Codex CLI, fully wired
copillm copilot      # launches GitHub Copilot CLI with your stored token
copillm pi           # launches the pi coding agent, fully wired

copillm will:

Auto-start its background daemon on http://127.0.0.1:4141
Resolve (or install) the latest agent binary into ~/.copillm/bin/
Inject the required environment variables (ANTHROPIC_BASE_URL, CODEX_HOME, etc.)
Hand the TTY to the agent

Why copillm?

One subscription, every agent. Run Claude Code, Codex CLI, and other compatible tools without managing separate Anthropic, OpenAI, and Copilot API keys.
Local-first. All traffic stays on 127.0.0.1; no third-party servers are involved.
Drop-in compatibility. Existing scripts that target api.openai.com or api.anthropic.com work by changing the base URL.
Live model catalogue. Models are discovered live from Copilot’s /models endpoint, including 1M-context Claude variants.

Documentation

Getting started — installation, authentication, first run
Commands — every command, grouped by domain (auth, claude, codex, copilot, pi, daemon, env, models, config)
Using with Claude Code — environment wiring and the [1m] 1M-context alias
Using with Codex CLI — environment wiring and config.toml generation
MCP & agent.toml — declare MCP servers once, fan out to every agent
HTTP API reference — endpoints and translation behaviour
Development & CI — building from source, PR gate, upstream e2e, release pipeline

Disclaimer. copillm is an independent, unofficial client of GitHub Copilot’s private API. It is not affiliated with, endorsed by, or supported by GitHub, Microsoft, OpenAI, or Anthropic. The upstream API may change at any time without notice. Use this project at your own risk.