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

A proxy server that lets you use Anthropic clients with multiple LLM providers via LiteLLM. 🌉

• OpenAI API key 🔑 (if using OpenAI provider)
• Google AI Studio (Gemini) API key 🔑 (if using Google provider)
• Google Cloud Project with Vertex AI API enabled 🔑 (if using Vertex AI provider)
• xAI API key 🔑 (if using xAI provider)
• uv installed.

1. Clone this repository:

   git clone https://github.com/CogAgent/claude-code-proxy.git
   cd claude-code-proxy

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).
   • XAI_API_KEY: Your xAI API key (Required if PREFERRED_PROVIDER=xai).

   For Vertex AI:

   • VERTEX_PROJECT_ID: Your Google Cloud Project ID (Required if PREFERRED_PROVIDER=vertex).
   • VERTEX_LOCATION: Region where your Vertex AI resources are located (defaults to us-central1).
   • Set up Application Default Credentials (ADC) with gcloud auth application-default login or set GOOGLE_APPLICATION_CREDENTIALS to point to your service account key file.

   Provider and Model Configuration:

   • PREFERRED_PROVIDER (Optional): Set to openai (default), google, vertex, or xai. This determines the primary backend for mapping haiku/sonnet.
   • BIG_MODEL (Optional): The model to map sonnet requests to. Defaults vary by provider.
   • SMALL_MODEL (Optional): The model to map haiku requests to. Defaults vary by provider.

   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 PREFERRED_PROVIDER=vertex, haiku/sonnet map to SMALL_MODEL/BIG_MODEL prefixed with vertex_ai/.
   • If PREFERRED_PROVIDER=xai, haiku/sonnet map to SMALL_MODEL/BIG_MODEL prefixed with xai/.

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. 🎯

The proxy automatically maps Claude models to OpenAI, Gemini, Vertex AI, or xAI models based on the configured provider:

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 Vertex AI models are supported with automatic vertex_ai/ prefix handling:

• gemini-2.5-pro-preview-03-25
• gemini-2.5-flash-preview-04-17
• gemini-2.0-flash
• gemini-1.5-flash-preview-0514
• gemini-1.5-pro-preview-0514

The following xAI models are supported with automatic xai/ prefix handling:

• grok-3-mini-beta
• grok-3-beta
• grok-2-vision-latest
• grok-2
• grok-1

The proxy automatically adds the appropriate prefix to model names:

• OpenAI models get the openai/ prefix
• Gemini models get the gemini/ prefix
• Vertex AI models get the vertex_ai/ prefix
• xAI models get the xai/ prefix
• The BIG_MODEL and SMALL_MODEL will get the appropriate prefix based on the provider and 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 or vertex_ai/gemini-2.5-pro-preview-03-25 depending on the provider
• grok-3 becomes xai/grok-3

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

Example 1: Default (Use OpenAI)

OPENAI_API_KEY="your-openai-key"
# 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: Use Google AI Studio

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: Use Vertex AI

VERTEX_PROJECT_ID="your-gcp-project-id"
VERTEX_LOCATION="us-central1"
# Set GOOGLE_APPLICATION_CREDENTIALS or use gcloud auth application-default login
PREFERRED_PROVIDER="vertex"
BIG_MODEL="gemini-2.5-pro-preview-03-25"
SMALL_MODEL="gemini-2.0-flash"

Example 4: Use xAI

XAI_API_KEY="your-xai-api-key"
PREFERRED_PROVIDER="xai"
BIG_MODEL="grok-3"
SMALL_MODEL="grok-3-mini-beta"

Example 5: Use Specific OpenAI Models

OPENAI_API_KEY="your-openai-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 the appropriate format via LiteLLM 🔄
3. Sending the translated request to the selected provider (OpenAI, Gemini, Vertex AI, or xAI) 📤
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. It also handles provider-specific authentication and configuration requirements. 🌊

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