Claude Code Proxy

A proxy server that enables Claude Code to work with OpenAI-compatible API providers. Convert Claude API requests to OpenAI API calls, allowing you to use various LLM providers through the Claude Code CLI.

Features

• Full Claude API Compatibility: Complete /v1/messages endpoint support
• Multiple Provider Support: OpenAI, Azure OpenAI, local models (Ollama), and any OpenAI-compatible API
• Smart Model Mapping: Configure BIG and SMALL models via environment variables
• Function Calling: Complete tool use support with proper conversion
• Streaming Responses: Real-time SSE streaming support
• Image Support: Base64 encoded image input
• Custom Headers: Automatic injection of custom HTTP headers for API requests
• Error Handling: Comprehensive error handling and logging

Quick Start

1. Install Dependencies

# Using UV (recommended)
uv sync

# Or using pip
pip install -r requirements.txt

2. Configure

cp .env.example .env
# Edit .env and add your API configuration
# Note: Environment variables are automatically loaded from .env file

3. Start Server

# Direct run
python start_proxy.py

# Or with UV
uv run claude-code-proxy

# Or with docker compose
docker compose up -d

4. Use with Claude Code

# If ANTHROPIC_API_KEY is not set in the proxy:
ANTHROPIC_BASE_URL=http://localhost:8082 ANTHROPIC_API_KEY="any-value" claude

# If ANTHROPIC_API_KEY is set in the proxy:
ANTHROPIC_BASE_URL=http://localhost:8082 ANTHROPIC_API_KEY="exact-matching-key" claude

Configuration

The application automatically loads environment variables from a .env file in the project root using python-dotenv. You can also set environment variables directly in your shell.

Environment Variables

Required:

• OPENAI_API_KEY - Your API key for the target provider

Security:

• ANTHROPIC_API_KEY - Expected Anthropic API key for client validation
  • If set, clients must provide this exact API key to access the proxy
  • If not set, any API key will be accepted

Model Configuration:

• BIG_MODEL - Model for Claude opus requests (default: gpt-4o)
• MIDDLE_MODEL - Model for Claude opus requests (default: gpt-4o)
• SMALL_MODEL - Model for Claude haiku requests (default: gpt-4o-mini)

API Configuration:

• OPENAI_BASE_URL - API base URL (default: https://api.openai.com/v1)

Server Settings:

• HOST - Server host (default: 0.0.0.0)
• PORT - Server port (default: 8082)
• LOG_LEVEL - Logging level (default: WARNING)

Performance:

• MAX_TOKENS_LIMIT - Token limit (default: 4096)
• REQUEST_TIMEOUT - Request timeout in seconds (default: 90)

Custom Headers:

• CUSTOM_HEADER_* - Custom headers for API requests (e.g., CUSTOM_HEADER_ACCEPT, CUSTOM_HEADER_AUTHORIZATION)
  • Uncomment in .env file to enable custom headers

Custom Headers Configuration

Add custom headers to your API requests by setting environment variables with the CUSTOM_HEADER_ prefix:

# Uncomment to enable custom headers
# CUSTOM_HEADER_ACCEPT="application/jsonstream"
# CUSTOM_HEADER_CONTENT_TYPE="application/json"
# CUSTOM_HEADER_USER_AGENT="your-app/1.0.0"
# CUSTOM_HEADER_AUTHORIZATION="Bearer your-token"
# CUSTOM_HEADER_X_API_KEY="your-api-key"
# CUSTOM_HEADER_X_CLIENT_ID="your-client-id"
# CUSTOM_HEADER_X_CLIENT_VERSION="1.0.0"
# CUSTOM_HEADER_X_REQUEST_ID="unique-request-id"
# CUSTOM_HEADER_X_TRACE_ID="trace-123"
# CUSTOM_HEADER_X_SESSION_ID="session-456"

Header Conversion Rules

Environment variables with the CUSTOM_HEADER_ prefix are automatically converted to HTTP headers:

• Environment variable: CUSTOM_HEADER_ACCEPT

• HTTP Header: ACCEPT

• Environment variable: CUSTOM_HEADER_X_API_KEY

• HTTP Header: X-API-KEY

• Environment variable: CUSTOM_HEADER_AUTHORIZATION

• HTTP Header: AUTHORIZATION

Supported Header Types

• Content Type: ACCEPT, CONTENT-TYPE
• Authentication: AUTHORIZATION, X-API-KEY
• Client Identification: USER-AGENT, X-CLIENT-ID, X-CLIENT-VERSION
• Tracking: X-REQUEST-ID, X-TRACE-ID, X-SESSION-ID

Usage Example

# Basic configuration
OPENAI_API_KEY="sk-your-openai-api-key-here"
OPENAI_BASE_URL="https://api.openai.com/v1"

# Enable custom headers (uncomment as needed)
CUSTOM_HEADER_ACCEPT="application/jsonstream"
CUSTOM_HEADER_CONTENT_TYPE="application/json"
CUSTOM_HEADER_USER_AGENT="my-app/1.0.0"
CUSTOM_HEADER_AUTHORIZATION="Bearer my-token"

The proxy will automatically include these headers in all API requests to the target LLM provider.

Model Mapping

The proxy maps Claude model requests to your configured models:

Claude Request	Mapped To	Environment Variable
Models with "haiku"	SMALL_MODEL	Default: gpt-4o-mini
Models with "sonnet"	MIDDLE_MODEL	Default: BIG_MODEL
Models with "opus"	BIG_MODEL	Default: gpt-4o

Provider Examples

OpenAI

OPENAI_API_KEY="sk-your-openai-key"
OPENAI_BASE_URL="https://api.openai.com/v1"
BIG_MODEL="gpt-4o"
MIDDLE_MODEL="gpt-4o"
SMALL_MODEL="gpt-4o-mini"

Azure OpenAI

OPENAI_API_KEY="your-azure-key"
OPENAI_BASE_URL="https://your-resource.openai.azure.com/openai/deployments/your-deployment"
BIG_MODEL="gpt-4"
MIDDLE_MODEL="gpt-4"
SMALL_MODEL="gpt-35-turbo"

Local Models (Ollama)

OPENAI_API_KEY="dummy-key"  # Required but can be dummy
OPENAI_BASE_URL="http://localhost:11434/v1"
BIG_MODEL="llama3.1:70b"
MIDDLE_MODEL="llama3.1:70b"
SMALL_MODEL="llama3.1:8b"

Other Providers

Any OpenAI-compatible API can be used by setting the appropriate OPENAI_BASE_URL.

Usage Examples

Basic Chat

import httpx

response = httpx.post(
    "http://localhost:8082/v1/messages",
    json={
        "model": "claude-3-5-sonnet-20241022",  # Maps to MIDDLE_MODEL
        "max_tokens": 100,
        "messages": [
            {"role": "user", "content": "Hello!"}
        ]
    }
)

Integration with Claude Code

This proxy is designed to work seamlessly with Claude Code CLI:

# Start the proxy
python start_proxy.py

# Use Claude Code with the proxy
ANTHROPIC_BASE_URL=http://localhost:8082 claude

# Or set permanently
export ANTHROPIC_BASE_URL=http://localhost:8082
claude

Testing

Test proxy functionality:

# Run comprehensive tests
python src/test_claude_to_openai.py

Development

Using UV

# Install dependencies
uv sync

# Run server
uv run claude-code-proxy

# Format code
uv run black src/
uv run isort src/

# Type checking
uv run mypy src/

Project Structure

claude-code-proxy/
├── src/
│   ├── main.py                     # Main server
│   ├── test_claude_to_openai.py    # Tests
│   └── [other modules...]
├── start_proxy.py                  # Startup script
├── .env.example                    # Config template
└── README.md                       # This file

Performance

• Async/await for high concurrency
• Connection pooling for efficiency
• Streaming support for real-time responses
• Configurable timeouts and retries
• Smart error handling with detailed logging

License

MIT License