Backend for Frontend (BFF)

A Backend for Frontend (BFF) is a dedicated API layer built to serve one specific client — your web app, your mobile app, a partner integration — rather than exposing one general-purpose API to all of them. Each frontend gets its own backend that sits between the client and your downstream services, calling them, aggregating the results, and reshaping the response into exactly what that client needs. The problem it solves is mismatch: a mobile app wants small, battery-friendly payloads and fewer round trips, while a web dashboard wants rich, denormalized data; forcing both through one API means one is always over- or under-served. A BFF lets each evolve independently — the mobile team can change its endpoints without breaking the web team. For SaaS builders integrating many internal or third-party services, a BFF is also a clean place to centralize authentication, rate-limit handling, caching, and combining several upstream APIs into one call. The cost is another service to build and maintain, so it earns its keep once you have genuinely divergent clients.