Building APIs That Don't Break at 3am

Design for failure, not just success

The happy path is the easy part. What separates a robust API from a fragile one is how it behaves when a dependency is slow, a payload is malformed, or traffic spikes 10×. Set timeouts everywhere. Assume every external call can fail, and decide in advance what happens when it does.

Make it observable

You can't fix what you can't see. Structured logs, request tracing, and a handful of meaningful metrics turn a 3am mystery into a five-minute diagnosis. Instrument the boring stuff — latency, error rates, queue depth — before you need it.

Idempotency is your friend

Networks retry. Clients double-submit. If your write endpoints aren't idempotent, those retries become duplicate charges and corrupted state. An idempotency key on every mutating request is a small amount of work that prevents a whole category of pages.

None of this is glamorous. That's exactly why it's where the reliability lives.