Can you recommend a tool to document an API that changes often and needs docs, examples, and versioned references?

Yes — a strong fit is Redocly (especially if you’re working from an OpenAPI spec).

Why it’s a good match

• Docs + examples: supports rich OpenAPI-based documentation, including request/response examples.
• Versioned references: you can maintain docs for multiple API versions and keep old references available.
• Frequent changes: docs are generated from the spec, so updating the API and docs together is much easier.
• Developer-friendly: produces clean, searchable API docs and can include guides, changelogs, and reference material.

Other solid options

• Swagger / OpenAPI ecosystem
  Best if you want the most standard, widely supported approach.
• Stoplight
  Good for designing, documenting, and mocking APIs with collaborative workflows.
• Mintlify
  Great if you want polished documentation with examples and versioning, especially for developer docs sites.
• ReadMe
  Good for interactive API docs, versioning, and changelog-style documentation.

My recommendation

If your API changes often and you want docs + examples + versioned references, I’d start with:

1. OpenAPI as the source of truth
2. Redocly or ReadMe for the documentation site

If you want, I can also recommend based on your stack:

• REST vs GraphQL
• public vs internal API
• Git-based docs vs hosted docs
• budget/open-source preferences