What is composer-api?

Cursor is a code editor that includes an AI assistant called Composer 2.5, but Cursor does not offer that AI as a general-purpose API endpoint that other tools can call. This project bridges that gap. It runs as a small server (a Cloudflare Worker) that accepts requests in the standard OpenAI format and translates them into the internal format that Cursor uses, then streams the response back to the caller. The live deployment is hosted at cursor-api.standardagents.ai. The practical effect is that any tool or library that already knows how to talk to OpenAI can be pointed at this server instead. You supply your own Cursor API key as the authentication token. The key is forwarded directly to Cursor per request and is not stored by the server. The supported endpoints are the standard chat completions endpoint, the responses endpoint, and a models list endpoint. The available model name is composer-2.5. The project includes a second route specifically for a tool called OpenCode. That route keeps a stable conversation identifier across multiple messages, which OpenCode needs to manage its own tool-execution loop locally while still using Composer as the underlying language model. A few OpenAI features are intentionally not supported because Cursor does not expose them through this path: requesting multiple completions at once, log probability outputs, audio output, and background jobs. Token usage counts in responses are estimated from character counts rather than exact token accounting, because Cursor's stream does not include that data. The server is built on Cloudflare's Worker platform and uses a Cloudflare D1 database for an optional legacy flow that stores encrypted keys. Deploying your own instance requires a Cloudflare account, a private Cursor backend URL (which is not public), and a few Wrangler secrets. The README lists the required configuration values and the build and deploy commands.