API Documentation

API documentation is the human-facing guide to an integration. It explains how to authenticate, names the base URL and environments, lists endpoints and fields, shows real requests and responses, and states limits, errors, pagination, retries, and webhook behavior. The best references let a developer make a successful test call without guessing. Stripe set the modern template with its three-column reference: prose on the left, parameters in the middle, and a runnable code sample in your language pinned on the right.

An OpenAPI file can generate the endpoint reference, but it is not the whole guide. People also need a quickstart, copyable examples, an authentication walkthrough, common workflows, and an explanation of what happens when things fail. Write for the order an integrator meets the system, not the order the backend happens to be organized.

The gotcha is drift. A polished example with an old field name is worse than no example because readers trust it and debug themselves. Generate reference tables from the OpenAPI contract, run example requests against a sandbox in CI, state the API version beside each sample, and give changed or removed behavior a dated migration note.