Detailed Review of Haystack - AI Code Assistant Software (2026)

What is Haystack?

Haystack gives your coding agent hundreds of copies of your app, each set up like one of your customers. Haystack gives your coding agent hundreds of copies of your app, each set up like one of your customers. Fork your infrastructure. Haystack snapshots your services and the data behind them, from Postgres and Redis to queues and object storage, then forks that snapshot once per case. Fourteen copies of prod, ready in 26 seconds. These are real environments, not mocks, and nothing that happens inside one reaches prod.