engineering
Idempotency keys let clients retry safely without producing duplicate side effects. The basic mechanism is straightforward, but the production patterns — handling in-flight duplicates, response caching, key scoping, expiry — have failure modes that aren't obvious until you've debugged them.
engineering
Most WebSocket implementations work fine in development and break in production at the boundaries: load balancer assignment, reconnection after network blips, server restarts, scaling beyond a single instance. The patterns that survive aren't complicated, but they aren't optional either.
engineering
Most pagination bugs come from clients constructing or modifying tokens in ways that look reasonable but break when the underlying data changes. Tokens that the server can verify and reject cleanly are the difference between a robust API and a fragile one.
engineering
Throttling and rate limiting look similar from the outside but solve different problems. Confusing them produces APIs that are technically protected but practically unusable, or APIs that look fair but quietly let one customer take down a shared dependency.
engineering
The choice between polling and webhooks looks like a technical decision but is actually about who bears the cost of latency and reliability. The patterns that hold up are the ones that match the cost-bearer to the party with the most leverage.
engineering
Schema-first puts the OpenAPI document at the center and generates server stubs and client SDKs from it. Code-first writes the server in your favorite framework and generates the spec from annotations. The right answer depends on who reads the spec and how often it changes.
engineering
Most API teams configure Cache-Control once when they ship the API and never touch HTTP caching again. The result is one of two failure modes: caches that lie because the freshness window was set without thinking, or caches that do nothing because everything is marked private no-cache. Both modes leave
engineering
Most webhook integrations start with one URL hardcoded in a settings page. Then customers ask for per-event routing, per-environment filtering, retry visibility, and the schema that started as a single text field becomes a subscription system. Here is the migration path.
engineering
GraphQL gets sold as the modern replacement for REST. The honest comparison is messier — GraphQL solves a real problem at large scale, creates several new problems at any scale, and is mostly the wrong default for the kind of API a small team actually needs to ship.
engineering
HTTP compression is one of the highest-leverage performance optimizations available, and one of the easiest to implement badly. The honest design space involves Brotli vs gzip selection, what not to compress, the CPU-versus-bandwidth trade-off, and the webhook-signature problem m...
engineering
Most webhook documentation focuses on the sender. The consumer side has its own design space — ack-fast queueing, idempotency by event ID, signature verification on raw bytes, and a small set of patterns that distinguish receivers that quietly drop events from receivers that surv...
engineering
File uploads look like a solved problem and turn into the most consistent source of production incidents in any web service. The honest design space involves validation, streaming, storage isolation, and a long list of failure modes that the framework defaults paper over.