OpenAPI validator

Validation tells you whether a definition is legal OpenAPI. It does not tell you whether the API is any good — a document can parse perfectly and still have no operation IDs, undocumented parameters, no error responses, and nobody to email when it breaks. This does both: syntax and schema errors are reported separately from a design score out of 100, with what each violation costs, and fixes applied for the ones whose correct answer follows from the document itself. Runs on Swagger 2.0, OpenAPI 3.0, 3.1 and 3.2.

Swagger 2.0, OpenAPI 3.0, 3.1 and 3.2, in JSON or YAML, detected automatically

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

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

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

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

Definitions you type, paste, or open from a local file are parsed, scored, and deterministically fixed in your browser. Import from URL sends the URL to Postman’s Cloud Agent, which fetches the definition and returns it to the editor. Draft with AI is separate and explicit: it sends the relevant excerpts to Postman for processing by an AI model. No account is needed.

Three per day without an account. Scoring and the deterministic auto-fixes are unlimited