Use Anthropic clients (like Claude Code) with Gemini, OpenAI, or Ollama backends. 🤝

A proxy server that lets you use Anthropic clients with Gemini, OpenAI, or Ollama models via LiteLLM. 🌉

• OpenAI API key 🔑
• Google AI Studio (Gemini) API key (if using Google provider) 🔑
• Ollama installed locally or on a server (if using Ollama provider) 🔗
• uv installed.

1. Clone this repository:

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

2. Install uv (if you haven't already):

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

   (uv will handle dependencies based on pyproject.toml when you run the server)

3. Configure Environment Variables: Copy the example environment file:

   cp .env.example .env

   Edit .env and fill in your API keys and model configurations:

   • ANTHROPIC_API_KEY: (Optional) Needed only if proxying to Anthropic models.
   • OPENAI_API_KEY: Your OpenAI API key (Required if using the default OpenAI preference or as fallback).
   • GEMINI_API_KEY: Your Google AI Studio (Gemini) API key (Required if PREFERRED_PROVIDER=google).
   • OLLAMA_API_BASE: (Optional) The URL of your Ollama instance (Default: "http://localhost:11434").
   • PREFERRED_PROVIDER (Optional): Set to openai (default), google, or ollama. This determines the primary backend for mapping haiku/sonnet.
   • BIG_MODEL (Optional): The model to map sonnet requests to. Defaults to gpt-4.1 (if PREFERRED_PROVIDER=openai), gemini-2.5-pro-preview-03-25 (if PREFERRED_PROVIDER=google), or can be set to an Ollama model like llama3.
   • SMALL_MODEL (Optional): The model to map haiku requests to. Defaults to gpt-4.1-mini (if PREFERRED_PROVIDER=openai), gemini-2.0-flash (if PREFERRED_PROVIDER=google), or can be set to an Ollama model like llama3:8b.

   Mapping Logic:

   • If PREFERRED_PROVIDER=openai (default), haiku/sonnet map to SMALL_MODEL/BIG_MODEL prefixed with openai/.
   • If PREFERRED_PROVIDER=google, haiku/sonnet map to SMALL_MODEL/BIG_MODEL prefixed with gemini/ if those models are in the server's known GEMINI_MODELS list (otherwise falls back to OpenAI mapping).
   • If PREFERRED_PROVIDER=ollama, haiku/sonnet map to SMALL_MODEL/BIG_MODEL prefixed with ollama/ if those models are in the server's known OLLAMA_MODELS list (otherwise falls back to OpenAI mapping).

4. Run the server:

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

   (--reload is optional, for development)

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 the configured backend models (defaulting to Gemini) through the proxy. 🎯

This guide shows you how to use Claude Code with Ollama as the backend.

1. Install Ollama from https://ollama.com/
2. Pull the models you want to use:

   ollama pull llama3
   ollama pull llama3:8b
   # Or any other models you want to use

3. (Optional) Configure Ollama context length:

   export OLLAMA_CONTEXT_LENGTH=30000  # adjust as needed for your prompts

4. Start Ollama server:

   ollama serve

1. Configure the proxy in the .env file:

   PREFERRED_PROVIDER="ollama"
   OLLAMA_API_BASE="http://localhost:11434"  # Change if using remote Ollama
   BIG_MODEL="llama3"      # For Claude Sonnet
   SMALL_MODEL="llama3:8b" # For Claude Haiku
   

2. Start the proxy server:

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

3. Connect with Claude Code:

   ANTHROPIC_BASE_URL=http://localhost:8082 claude

The proxy supports these Ollama models out of the box:

• llama3
• llama3:8b
• llama3:70b
• llama2
• mistral
• mistral:instruct
• mixtral
• mixtral:instruct
• phi3:mini
• phi3:medium

To use other models, add them to the OLLAMA_MODELS list in server.py.

• Make sure Ollama is running with ollama serve
• Check if you can access Ollama directly: curl http://localhost:11434/api/tags
• If using a remote Ollama server, ensure the URL is correct in OLLAMA_API_BASE

The proxy automatically maps Claude models to OpenAI, Gemini, or Ollama models based on the configured model:

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
• gpt-4.1
• gpt-4.1-mini

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

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

The following Ollama models are supported with automatic ollama/ prefix handling:

• llama3
• llama3:8b
• llama3:70b
• llama2
• mistral
• mistral:instruct
• mixtral
• mixtral:instruct
• phi3:mini
• phi3:medium

The proxy automatically adds the appropriate prefix to model names:

• OpenAI models get the openai/ prefix
• Gemini models get the gemini/ prefix
• Ollama models get the ollama/ prefix
• The BIG_MODEL and SMALL_MODEL will get the appropriate prefix based on whether they're in the OpenAI, Gemini, or Ollama 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
• llama3 becomes ollama/llama3
• When BIG_MODEL is set to a Gemini model, Claude Sonnet will map to gemini/[model-name]
• When BIG_MODEL is set to an Ollama model, Claude Sonnet will map to ollama/[model-name]

Control the mapping using environment variables in your .env file or directly:

Example 1: Default (Use OpenAI) No changes needed in .env beyond API keys, or ensure:

OPENAI_API_KEY="your-openai-key"
GEMINI_API_KEY="your-google-key" # Needed if PREFERRED_PROVIDER=google
# PREFERRED_PROVIDER="openai" # Optional, it's the default
# BIG_MODEL="gpt-4.1" # Optional, it's the default
# SMALL_MODEL="gpt-4.1-mini" # Optional, it's the default

Example 2: Prefer Google

GEMINI_API_KEY="your-google-key"
OPENAI_API_KEY="your-openai-key" # Needed for fallback
PREFERRED_PROVIDER="google"
# BIG_MODEL="gemini-2.5-pro-preview-03-25" # Optional, it's the default for Google pref
# SMALL_MODEL="gemini-2.0-flash" # Optional, it's the default for Google pref

Example 3: Prefer Ollama

PREFERRED_PROVIDER="ollama"
OLLAMA_API_BASE="http://localhost:11434" # Optional, this is the default
OPENAI_API_KEY="your-openai-key" # Needed for fallback
BIG_MODEL="llama3" # Choose your Ollama model
SMALL_MODEL="llama3:8b" # Choose your Ollama model

Example 4: Use Specific OpenAI Models

OPENAI_API_KEY="your-openai-key"
GEMINI_API_KEY="your-google-key"
PREFERRED_PROVIDER="openai"
BIG_MODEL="gpt-4o" # Example specific model
SMALL_MODEL="gpt-4o-mini" # Example specific model

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. 🌊

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