The free API docs stack
teams actually ship with
Free OpenAPI engine for interactive docs, lint, mock, and diff. Embed on your site or self-host — no seats, no signup wall, MIT licensed.
Reference
⌘K search · try-it · SDKs
Linter
Score A–F · fix before publish
Mock + Diff
Ship UI while API evolves
Full product suite
Not just a docs skin — tooling around the OpenAPI lifecycle.
Reference
Interactive OpenAPI docs with try-it-out, models, auth schemes, and dual layouts.
Linter
Quality score your spec — operationIds, servers, path params, responses, and more.
Mock
Return example payloads from your OpenAPI without standing up a backend.
Diff
Compare two OpenAPI versions. See added, removed, and changed operations.
Catalog & embed
Sample APIs plus iframe embeds for any public OpenAPI URL — no account.
Docs platform
Self-host on Vercel, theme dark/light, environments, history, 10 SDK languages.
Why teams choose Aperio
No gatekeeping
No seats, no trial wall, no “talk to sales” for basic docs. Free forever under MIT.
Minutes, not weeks
Paste a spec and ship interactive docs immediately. Lint and mock in the same browser tab.
Own your stack
Self-host, white-label, or embed. Your domain, your branding, your OpenAPI source of truth.
- Interactive API referenceIncluded
- Try-it-out clientIncluded
- Multi-language code samplesIncluded
- OpenAPI linter / scoreIncluded
- Mock from OpenAPIIncluded
- Spec diff / changelog assistIncluded
- Embed without accountIncluded
- Self-host (MIT)Included
- $0 with full featuresIncluded
Built for developers
Ship API docs that match your product quality
Free forever. Open source. No credit card. Compete on product — not on documentation tooling bills.