What is claude2api?

Claude2api is a small service written in the Go programming language that acts as a middleman between your application and the claude.ai website. Instead of calling an official developer API, it takes requests in common formats used by OpenAI and Anthropic, forwards them to the claude.ai web interface, and passes the answers back. You need an existing claude.ai browser session for it to work, since the service relies on your login credentials to reach Claude through its normal web pages. The project mimics a real web browser when contacting claude.ai. It sends matching security settings, headers, and cookies so the upstream site treats the traffic like a normal visitor. You can authenticate in two ways: by providing just a session key, which is simpler but less precise, or by pasting a full set of browser cookies, which closely matches real browser behavior. Certain security cookies from services like Cloudflare are never faked or forwarded in the simpler mode. It exposes several familiar endpoints, including chat completion and message interfaces that match OpenAI and Anthropic conventions, plus a model list endpoint. Responses can come back all at once or as a streaming event feed. A persistent conversation mode keeps multi-turn chats connected. Only a fixed set of Claude model names are accepted, and anything else returns an error. Running it requires Go 1.26.4 or later, or you can use the provided Docker image and Docker Compose setup. Configuration is handled through environment variables for the port, upstream URL, session key, full cookie string, timezone, locale, and default model. Each request creates a temporary claude.ai session and tries to delete it afterward. Token counts in the usage data are rough estimates based on output length. The project does not appear to have a detailed description on GitHub beyond the README itself.