Designing APIs Your Partners Will Love
Naming, versioning and error design that make integrations quick instead of painful.
Sara Thomas · · 6 min read
An API is a product with developers as its users. The best ones feel obvious: you guess the endpoint and you’re right. That isn’t luck; it comes from a few deliberate habits.
Be boringly consistent
Pick conventions and never break them: plural resource names, the same casing everywhere, the same pagination shape on every list. Consistency is what lets a developer learn one endpoint and understand ten.
Make errors useful
An error should tell the developer what went wrong and how to fix it. We return a stable machine-readable code, a human message and, where possible, the field at fault. “Invalid request” helps nobody; “amount must be a positive integer in paise” saves an afternoon.
Version from day one
Add a version to the path or header before your first partner integrates. Then follow two rules: never change the meaning of an existing field, and give at least six months’ notice before removing anything.
Idempotency for anything that matters
Payments, orders and bookings should accept an idempotency key so a retried request never charges twice. It’s a small addition that prevents the most expensive class of integration bugs.
Documentation is part of the API
Generate reference docs from the schema so they never drift, then add a short getting-started guide with a working request someone can copy and paste. Time to first successful call is the metric that matters.
Need an API your partners can integrate in a day? Let’s talk.