claude-code-proxy/README.md

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
   # For OpenAI models (default)
   # BIG_MODEL=gpt-4o
   # SMALL_MODEL=gpt-4o-mini
   
   # For Gemini models
   # BIG_MODEL=gemini-2.5-pro-preview-03-25
   # SMALL_MODEL=gemini-2.0-flash
   

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 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 either OpenAI or Gemini models based on the configured model:

Claude Model	Default Mapping	When BIG_MODEL/SMALL_MODEL is a Gemini model
haiku	openai/gpt-4o-mini	gemini/[model-name]
sonnet	openai/gpt-4o	gemini/[model-name]

Supported Models

OpenAI Models

The following OpenAI models are supported with automatic openai/ prefix handling:

• o3-mini
• o1
• o1-mini
• o1-pro
• gpt-4.5-preview
• gpt-4o
• gpt-4o-audio-preview
• chatgpt-4o-latest
• gpt-4o-mini
• gpt-4o-mini-audio-preview

Gemini Models

The following Gemini models are supported with automatic gemini/ prefix handling:

• gemini-2.5-pro-preview-03-25
• gemini-2.0-flash

Model Prefix Handling

The proxy automatically adds the appropriate prefix to model names:

• OpenAI models get the openai/ prefix
• Gemini models get the gemini/ prefix
• The BIG_MODEL and SMALL_MODEL will get the appropriate prefix based on whether they're in the OpenAI or Gemini model lists

For example:

• gpt-4o becomes openai/gpt-4o
• gemini-2.5-pro-preview-03-25 becomes gemini/gemini-2.5-pro-preview-03-25
• When BIG_MODEL is set to a Gemini model, Claude Sonnet will map to gemini/[model-name]

Customizing Model Mapping

You can customize which models are used via environment variables:

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

# For Gemini models
# BIG_MODEL=gemini-2.5-pro-preview-03-25
# SMALL_MODEL=gemini-2.0-flash

Or set them directly when running the server:

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

# Using Gemini models
BIG_MODEL=gemini-2.5-pro-preview-03-25 SMALL_MODEL=gemini-2.0-flash uv run uvicorn server:app --host 0.0.0.0 --port 8082

To use a mix of OpenAI and Gemini models:

BIG_MODEL=gemini-2.5-pro-preview-03-25 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. 🎁