OpenAPI validator

Validate an OpenAPI definition and score its design

Compare what you unlock

  • Linting and validationSyntax and schema errors listed as you edit
  • Design health scoreScore out of 100 with weighted rules
  • Spec formatsSwagger 2.0, OpenAPI 3.0 and 3.1
  • Auto-fixesMechanical fixes applied in the browser
  • AI documentationThree drafts per day
  • Spec storageNot included
  • Version controlNot included

FAQ

Which formats are supported?
Swagger 2.0, OpenAPI 3.0, and OpenAPI 3.1, in JSON or YAML, detected automatically
Can I import Swagger specs into Postman?
Yes. Postman imports Swagger 2.0 specifications directly — validate here first, then paste the same file into Postman to generate a Collection you can run, test, and keep in sync with the spec
How is the score calculated?
Every violated rule deducts a fixed weight once — 5 points for an error, 2 for a warning, 0.5 for a style issue — regardless of how many times it fires, so the score starts at 100 and falls by the sum of the rules you break
Why can it not auto-fix everything?
Because most violations need information that is not in the document. An operation ID can be derived from the method and path, but a description, a contact email or a licence cannot be — writing a placeholder would raise the score while making the definition wrong
Does auto-fix preserve my comments and formatting?
Yes for YAML: fixes are applied as targeted edits to the exact bytes that change, so comments, quote styles and indentation elsewhere are untouched. JSON has no comments, and is re-serialised at the indent it was written with
Is my API definition uploaded anywhere?
Scoring and the deterministic auto-fixes run entirely in your browser, so nothing is sent anywhere. The one exception is Draft with AI, which is a separate button: pressing it sends the specific gaps it is filling to a model. If you never press it, the definition never leaves your machine
How many AI drafts do I get?
Three per day without an account. Scoring and the deterministic auto-fixes are unlimited