polyclaude

Use OpenAI, Gemini, or any OpenAI-compatible model inside the Claude Code CLI.

Claude Code is a great terminal coding agent — but it only talks to Anthropic's models. polyclaude lets you keep the exact Claude Code experience (its UI, tools, and agent loop) while the actual model behind it is GPT, Gemini, a Groq model, an OpenRouter model, or a local Ollama model.

It works by running a tiny local proxy that speaks Claude Code's API on one side and your provider's API on the other, translating between them on the fly. Claude Code itself is never modified.

Claude Code  ⇄  Anthropic Messages API  ⇄  [ polyclaude ]  ⇄  OpenAI / Gemini / …

Install

pipx install polyclaude      # recommended
# or: uv tool install polyclaude
# or: pip install polyclaude

You'll also need Claude Code installed (claude on your PATH) and an API key for whichever provider you want to use.

Use

export GEMINI_API_KEY=...        # or OPENAI_API_KEY, GROQ_API_KEY, …
polyclaude --gemini              # Claude Code, powered by Gemini
polyclaude --openai              # …powered by GPT
polyclaude --openai --model gpt-4.1
polyclaude --gemini --model gemini-2.5-pro

That's it — you're dropped into a normal Claude Code session running on the model you chose. First run auto-configures the local proxy certificate; nothing else to set up.

Pass arguments straight through to claude after --:

polyclaude --gemini -- -p "explain this repo"

Providers

Any model your key can access works via --model, including the newest ones (Gemini 3.x, GPT-5.x). polyclaude handles the provider-specific details so tool calling and reasoning keep working:

• Gemini 3.x thinking models need their function-call thought signatures round-tripped across turns — handled automatically.
• GPT-5.5 / 5.6 can't use tools and reasoning together on the standard endpoint; polyclaude routes them through OpenAI's /responses API so you get both (tune depth with --reasoning low|medium|high).
• Reasoning models reject non-default sampling params — dropped automatically.
• Turns that hit the output-token cap are transparently continued.

Run polyclaude --list to see everything.

Specialize the agent

Give the agent a persona/use-case with a profile — it's appended to the system prompt for the main loop only, so Claude Code's own tooling keeps working:

polyclaude --gemini --profile datascience
polyclaude --openai --profile reviewer
polyclaude --gemini --profile ./my-profile.md      # your own file

Bundled profiles: datascience, reviewer, concise. Or replace the whole system prompt with --system path/to/file.md.

Resume a session

Claude Code keeps your conversations; resume them straight through polyclaude:

polyclaude --gemini --continue     # continue the most recent session
polyclaude --gemini --resume       # pick one from a list

Reskin (optional, cosmetic)

By default the welcome screen still reads "Claude Code" and shows a Claude model name even though another model is answering. --reskin recolors the UI, relabels it to polyclaude, and shows the real model name:

polyclaude --gemini --reskin              # green accent + polyclaude label
polyclaude --openai --reskin --hue 200    # a different accent colour

This is display-only — it rewrites the terminal output as it's drawn; the Claude Code binary is never modified and your keystrokes pass through untouched.

How it works

polyclaude starts mitmproxy locally with a small addon and points Claude Code at it (via HTTPS_PROXY + NODE_EXTRA_CA_CERTS, scoped to that one process). The addon intercepts requests to api.anthropic.com/v1/messages, translates the Anthropic request into the provider's format, calls the provider, and streams the reply back in Anthropic's event format. Every other host is passed straight through untouched.

Only sessions you launch with polyclaude are affected — your normal claude is unchanged and still uses Anthropic.

FAQ

Does this change my Claude Code install? No. It only sets proxy environment variables for the session it launches.

Do my keys leave my machine? Only to the provider you choose (Google, OpenAI, etc.), exactly as if you called their API directly. polyclaude has no servers.

Quality feels off on some models. Different models behave differently inside Claude Code's harness (its prompt and tools are tuned for Claude). Larger/newer models fare better; try --reasoning high on OpenAI and compare providers.

Can I use my own endpoint? Yes — anything OpenAI-compatible. Point at it and go (OpenRouter, vLLM, LM Studio, etc.).

Notes

For personal and development use, with your own API keys. Respect the terms of service of Claude Code and of whichever model provider you use.

License

MIT © Devesh Pratap