I'm building internal engineering docs for an API platform, what tool should I choose?

For internal engineering docs for an API platform, the best tool usually depends on whether you want speed and simplicity or structure and scale.

Good default choice

If you want one recommendation to start with:

Choose Notion or Confluence for internal docs, and pair it with OpenAPI/Swagger for API reference.

That gives you:

• human-friendly internal documentation
• easy collaboration and search
• a reliable way to keep API specs tied to the source of truth

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What to pick based on your needs

1. Notion

Best if you want:

• fast setup
• flexible pages
• good collaboration
• lightweight internal knowledge base

Pros:

• very easy to use
• great for linking docs, runbooks, RFCs, onboarding
• good for teams that move quickly

Cons:

• can get messy at scale
• weaker structure/governance than dedicated docs systems
• not ideal as the only place for formal API specs

2. Confluence

Best if you want:

• more structured enterprise documentation
• permissions and team organization
• formal process docs and architecture docs

Pros:

• strong for internal engineering orgs
• good permissions and hierarchy
• common in larger companies

Cons:

• can feel heavy and clunky
• editing experience is often disliked
• pages can become stale

3. GitBook

Best if you want:

• clean docs experience
• docs closer to engineering workflows
• markdown-based content with better presentation

Pros:

• nicer than Confluence for many teams
• good for docs-as-code style workflows
• easier to maintain than wiki-style tools

Cons:

• less flexible than Notion for mixed internal knowledge
• pricing can grow
• still not the spec source of truth for APIs

4. Docs-as-code with Markdown + GitHub/GitLab + Docusaurus/MkDocs

Best if you want:

• version-controlled docs
• docs reviewed like code
• strong engineering workflow
• long-term maintainability

Pros:

• docs live with the code
• PR reviews, history, approvals
• ideal if engineers maintain docs directly

Cons:

• less friendly for non-technical contributors
• more setup
• publishing and navigation need ownership

5. OpenAPI + Swagger / Redoc / Stoplight

Best for:

• API reference documentation
• endpoint-level documentation
• generated docs from schema/spec

Pros:

• excellent for API accuracy
• keeps reference docs in sync with implementation
• standard for REST APIs

Cons:

• not enough for broader internal documentation
• doesn’t replace architecture, design, or process docs

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Practical recommendation for an API platform

A strong setup is:

• Notion or Confluence for:

  • architecture overview
  • platform onboarding
  • internal design docs
  • runbooks
  • decision records
  • operational docs

• OpenAPI + Redoc/Swagger for:

  • API reference
  • endpoint docs
  • request/response examples

• Optional:

  • GitHub + Markdown for docs that need reviews and versioning

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If you want my opinion by team size

Small team / startup

• Notion + OpenAPI/Swagger
• fast, flexible, low friction

Mid-size engineering org

• GitBook or Confluence + OpenAPI
• better organization and governance

Large engineering org

• Docs-as-code + OpenAPI + internal wiki
• strongest maintainability and review process

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My short answer

If you're building internal engineering docs for an API platform, I’d usually choose:

Notion for internal knowledge + OpenAPI/Redoc for API specs
or
Docs-as-code (Markdown in Git + Docusaurus/MkDocs) + OpenAPI if engineering rigor matters most.

If you want, I can also give you:

1. a tool comparison table, or
2. a recommended stack based on your team size and workflow.