Claude Code and uttapen: why there is no direct route
Claude Code speaks only the Anthropic messages API, which uttapen does not serve. What that means, and the tools that do run Claude models.
Updated: 22 Sep 2026
Claude Code cannot be pointed at uttapen directly. It speaks only Anthropic's message-based API (/v1/messages), and uttapen doesn't serve that path. ANTHROPIC_BASE_URL only helps when the target actually implements that same API.
The details
uttapen is an OpenAI-compatible gateway serving /v1/chat/completions, /v1/completions, /v1/embeddings and /v1/models (compatibility and migration). Claude Code expects a different request and response shape; its own gateway guide says a gateway has to expose one of Anthropic's message-based formats.
The Claude models themselves are here, though. anthropic/claude-sonnet-5, anthropic/claude-opus-5 and anthropic/claude-haiku-4.5 work in any Chat Completions client — opencode, Cline, Kilo Code, Crush or Aider, for instance. The limitation is the Claude Code app, not the models.
Third-party bridges
Open-source projects exist that run on your own machine, accept message-format requests and translate them into Chat Completions (the LiteLLM proxy and claude-code-router among them). They can connect Claude Code to any OpenAI-compatible endpoint, but:
- we haven't tested them and don't support them;
- your uttapen key passes through an extra layer, so keep it to your own machine and use a key with a tight monthly cap (API keys);
- Claude Code's own vendor doesn't support routing the tool to models other than its own.
If a message-based path is ever added to uttapen, this page will be updated. The tools that work today are listed in integrations.
Sign up with a phone number, top up your wallet from 100,000 toman and create a key. Free models work without a top-up — up to 50 requests a day. Create an API key →