How to keep API docs up to date

API docs go stale faster than most documentation, because an API changes in small ways all the time. A renamed field, a new parameter, a changed default, and the docs are wrong. Here is how to keep API documentation up to date, split by the two parts every API doc has.

The two parts of API docs

Every API doc is really two things:

• The reference. The exact list of endpoints, parameters, types, and responses.
• The guides. The prose that explains how to authenticate, how to handle errors, and how to actually use the API.

They go stale in different ways and need different fixes. Most advice only covers the reference and ignores the guides, which is where the harder drift lives.

Keeping the reference current

The reference maps directly to your code, so generate it, do not write it by hand.

• Keep an OpenAPI spec as the source of truth and render it with Swagger UI or Redoc. When the API changes, update the spec and the reference follows.
• Better still, generate the spec from your code so there is one source. Then the reference can never drift from the implementation, because it comes from it.
• Run the generation in CI on every commit, so the published reference is always rebuilt from the current code.

Done well, your reference is never more than a commit behind your API. This part is close to a solved problem.

Keeping the guides current

This is the hard part. Your authentication guide, your error-handling page, and your tutorials are prose, not generated output. When you change how auth works or rename a concept, no generator fixes those pages. A person has to notice and rewrite them, and that is exactly what gets missed.

A few ways to handle it:

• Tie docs to code review. Make it a rule that an API change includes the doc update in the same pull request, so the guide changes with the code.
• Run your code samples as tests. If a sample in your docs stops working, the build fails, which catches the most visible kind of drift.
• Use a tool that fixes the prose automatically. uptodate reads the code changes you merge to GitHub, finds the guides a change made inaccurate, and opens a pull request with the fix. This targets exactly the part generators cannot reach, which is the written pages around the reference.

A checklist for current API docs

• Generate the reference from an OpenAPI spec or from code.
• Rebuild the reference in CI on every commit.
• Require doc updates in the same pull request as API changes.
• Run doc code samples as tests.
• Use an AI tool to catch and fix drift in the guides, reviewed as pull requests.

Why this matters more for APIs

API docs have low tolerance for error. A developer following a wrong example gets a failed call and loses trust immediately. With prose docs a reader can often work around a small mistake, but with an API a wrong parameter simply does not work. That is why keeping API docs current is worth automating properly rather than relying on someone to remember.

The short answer

Keep the reference current by generating it from a spec or code and rebuilding it in CI. Keep the guides current by tying doc updates to code review, testing your samples, and using a tool like uptodate to fix the prose your changes break. The reference is easy to automate. The guides are where a sync tool earns its keep.