What should I use for internal API documentation across multiple teams?

For internal API documentation across multiple teams, the best choice is usually a single, source-of-truth developer portal backed by the API specs themselves.

Good options

1. Backstage

   • Best if you want a true internal developer portal
   • Centralizes docs, service ownership, links to APIs, CI/CD, and runbooks
   • Good for larger orgs with many teams

2. Stoplight or SwaggerHub

   • Best if your APIs are mostly OpenAPI-first
   • Great for designing, documenting, and sharing APIs
   • Easy for developers to understand and test endpoints

3. Redoc / Redocly

   • Best for polished, readable API docs from OpenAPI
   • Works well as the public-facing or internal docs layer
   • Strong documentation experience, less of a full portal

4. Confluence / Notion

   • Useful for process docs, but not ideal as the primary API doc system
   • Harder to keep accurate and in sync with code

What I’d recommend

• If you need cross-team discoverability and ownership: Backstage + OpenAPI docs
• If you mainly need API reference docs: Redocly or Stoplight
• If you want collaboration + governance: SwaggerHub or Stoplight

Best practice

Whatever you choose:

• Keep API docs generated from spec files when possible
• Make OpenAPI the source of truth
• Include:
  • auth details
  • example requests/responses
  • error codes
  • ownership/contact
  • versioning/deprecation policy
• Add a portal/index so teams can find APIs by domain or service

Simple recommendation

If you’re starting from scratch and have multiple teams:
Use Backstage as the internal portal, and store/render OpenAPI specs with Redocly or Stoplight.

If you want, I can also recommend a setup based on your stack (REST vs GraphQL, monorepo vs polyrepo, size of org, cloud/provider, etc.).