claude-openai-proxy 0.1.5

Thin OpenAI-compatible API proxy backed by Anthropic Vertex AI

Claude OpenAI Proxy

A thin Python proxy that wraps the Anthropic Vertex AI SDK and exposes an OpenAI-compatible /v1/chat/completions API.

Requests are translated from the OpenAI message format to the Anthropic format, sent to Claude via the Vertex AI API, and the responses are converted back to OpenAI-compatible JSON (or SSE for streaming).

Prerequisites

• Python 3.11+
• A Google Cloud project with the Anthropic Vertex AI API enabled
• Google Cloud credentials configured (e.g. gcloud auth application-default login)

Install

pip install --user claude-openai-proxy

Make sure ~/.local/bin is in your PATH.

More options (uv tool, pipx, from source) are covered in the installation guide.

Run

claude-openai-proxy                          # localhost:1234
HOST=0.0.0.0 PORT=5000 claude-openai-proxy   # all interfaces, custom port

Endpoints

Method	Path	Description
GET	/health	Health check
GET	/v1/models	List available Claude models
POST	/v1/chat/completions	Chat completions (streaming + sync)

Development

uv sync --group dev

Lint

uv run ruff check .          # check for issues
uv run ruff check --fix .    # auto-fix issues

Format

uv run ruff format .         # format all files
uv run ruff format --check . # check without writing

Test

uv run pytest               # run all tests
uv run pytest -v            # verbose output

Environment Variables

Variable	Default	Description
HOST	127.0.0.1	Server listen address
PORT	1234	Server listen port
LOG_LEVEL	INFO	Python logging level
MAX_TOKENS	8192	Default max tokens per response
ANTHROPIC_TIMEOUT	600	Request timeout in seconds for the Anthropic SDK
CLOUD_ML_REGION	—	Google Cloud region (e.g. us-east5)
ANTHROPIC_VERTEX_PROJECT_ID	—	Google Cloud project ID