Claude Code but with OpenAI Models 🧙‍♂️🔄 ¯\(ツ)/¯

Use Claude Code with OpenAI Models 🤝

A proxy server that lets you use Claude Code with OpenAI models like GPT-4o / gpt-4.5 and o3-mini. 🌉

Quick Start ⚡

Prerequisites

• OpenAI API key 🔑

Setup 🛠️

1. Clone this repository:

   git clone https://github.com/1rgs/claude-code-openai.git
   cd claude-code-openai
   

2. Install UV:

    curl -LsSf https://astral.sh/uv/install.sh | sh
   

3. Configure your API keys: Create a .env file with:

   OPENAI_API_KEY=your-openai-key
   # Optional: customize which models are used
   # BIG_MODEL=gpt-4o
   # SMALL_MODEL=gpt-4o-mini
   

4. Start the proxy server:

   uv run uvicorn server:app --host 0.0.0.0 --port 8082
   

Using with Claude Code 🎮

1. Install Claude Code (if you haven't already):

   npm install -g @anthropic-ai/claude-code
   

2. Connect to your proxy:

   ANTHROPIC_BASE_URL=http://localhost:8082 DISABLE_PROMPT_CACHING=1 claude
   

3. That's it! Your Claude Code client will now use OpenAI models through the proxy. 🎯

Model Mapping 🗺️

The proxy automatically maps Claude models to OpenAI models:

Claude Model	OpenAI Model
haiku	gpt-4o-mini (default)
sonnet	gpt-4o (default)

Customizing Model Mapping

You can customize which OpenAI models are used via environment variables:

• BIG_MODEL: The OpenAI model to use for Claude Sonnet models (default: "gpt-4o")
• SMALL_MODEL: The OpenAI model to use for Claude Haiku models (default: "gpt-4o-mini")

Add these to your .env file to customize:

OPENAI_API_KEY=your-openai-key
BIG_MODEL=gpt-4o
SMALL_MODEL=gpt-4o-mini

Or set them directly when running the server:

BIG_MODEL=gpt-4o SMALL_MODEL=gpt-4o-mini uv run uvicorn server:app --host 0.0.0.0 --port 8082

How It Works 🧩

This proxy works by:

1. Receiving requests in Anthropic's API format 📥
2. Translating the requests to OpenAI format via LiteLLM 🔄
3. Sending the translated request to OpenAI 📤
4. Converting the response back to Anthropic format 🔄
5. Returning the formatted response to the client ✅

The proxy handles both streaming and non-streaming responses, maintaining compatibility with all Claude clients. 🌊

Contributing 🤝

Contributions are welcome! Please feel free to submit a Pull Request. 🎁