Windlass

Windlass is a Python backend for products built around agents that call tools. It uses FastAPI with LangGraph for agent flows, Postgres for state checkpoints, a tool registry with typed inputs, and an approval step so a human confirms risky actions like sending email. A small React front end shows runs step by step, with token counts and timings.

The maintainers are opinionated about observability: every run is stored and can be replayed with a different model for comparison. The limitation: it is not a full SaaS kit. Auth is a single API key, there is no billing and no teams, so you will pair it with another starter or build those parts yourself.