What should API documentation include?

Authentication, a first working request, every endpoint with parameters and example responses, error formats and rate limits.

How do you keep API docs from going out of date?

Keep the reference next to the work that changes it, link endpoints to tasks and review docs when the contract changes.

How to write API documentation developers use

API documentation is successful when a developer who has never seen your API can make a working request in minutes. Everything else supports that moment.

Key takeaways

Lead with authentication and a first working example.
Document every endpoint with real requests and responses.
Cover errors, limits and edge cases, not just the happy path.
Keep the reference alive by tying it to the work that changes it.

Start with the first request

Put a "quick start" at the top: how to get credentials and one request the reader can paste and run. A working first call builds trust and gives the reader a base to explore from.

bash

curl https://api.example.com/v1/projects \
  -H "Authorization: Bearer YOUR_TOKEN"

Show the response next to it so they can confirm they got it right.

Document each endpoint the same way

Consistency lets readers skim. For every endpoint include:

Method and path, and a one-line purpose.
Authentication and permissions needed.
Parameters: path, query and body, with types, required or optional, and constraints.
Example request in at least one language, plus curl.
Example response with realistic values.
Errors it can return, with the status code and what to do.

Cover the unhappy paths

Developers spend most of their time on failures. Explain:

the error response shape, once, in a shared section,
validation messages and what triggers them,
rate limits and how to back off,
idempotency and retries where they matter.

Explain concepts, not just endpoints

A list of endpoints does not tell a reader how to accomplish something. Add short guides for common jobs such as "create a project and add a task", showing the sequence of calls.

Let readers try it

A built-in request explorer where a developer can fill in parameters and send a call removes the distance between reading and doing. Environments (for example staging and production) let them test safely.

Keep it accurate

The hardest part is not writing docs; it is keeping them true. Tie the reference to the work:

Link each endpoint to the tasks that change it.
Add "docs updated" to the definition of done.
Review the reference when the contract changes.

Osco stores API endpoints alongside docs and tasks, with an explorer and environments for trying requests, and endpoints can be linked to the work that changes them. Share links let you give read-only access to partners without adding them to the workspace.

Conclusion

Write for the developer's first ten minutes, cover failures honestly and connect the reference to the work that changes it. Docs that stay accurate get used, and used docs get better.

How to write API documentation developers actually use