FastAPI for mobile backends

FastAPI gives typed request and response models, automatic OpenAPI docs, and async endpoints, useful when mobile clients hit your API from flaky networks and expect clear error shapes.

For mobile, standardize on bearer tokens or session cookies issued after Firebase Auth or your identity provider verifies the user. Validate every payload with Pydantic, return consistent HTTP status codes, and document error codes the app can branch on.

Add rate limiting at the edge or in middleware early. Mobile apps retry aggressively. Idempotent endpoints and request IDs save you from duplicate side effects. Keep heavy work off the request thread: queue jobs for embeddings, file processing, or long LLM calls and poll or push results to the client.

Teams reach for FastAPI when they outgrow Firebase-only backends but still need speed to market. Pairing the API with a senior mobile developer keeps contract types aligned on both sides of the wire.