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OpenAPI Validate

Validate an OpenAPI 3.0 or 3.1 document against the core spec rules. Catches the common shape errors (missing info, malformed paths, response status code typos) with clear paths and messages — without bundling the full 50 KB meta-schema. Set strict mode to also flag missing operationIds, descriptions, and other lints.

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About OpenAPI Validate

OpenAPI Validate checks an OpenAPI 3.0 or 3.1 document against the core spec rules, catching common shape errors like a missing info object, malformed paths, or response status-code typos, each reported with a clear path and message. It does this without bundling the full 50 KB meta-schema, so it's quick. Turn on strict mode to also flag missing operationIds, descriptions, and similar lints, and note that your spec is validated entirely in your browser.

Category
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Input
Accepts: application/json, application/yaml, text/yaml or text/plain.
Output
Outputs: application/json.
Cost
Free, runs in your browser
Memory
low
Privacy: OpenAPI Validate runs entirely on your device. Files you provide never leave your browser — no uploads, no server, no tracking. The page works offline once loaded.

Common uses

  • Catch a malformed path or missing info block before committing an API spec to your repo
  • Validate a hand-edited OpenAPI file that broke your code generator with an unhelpful error
  • Run strict mode to enforce that every operation has an operationId before generating clients
  • Check a YAML spec for response status-code typos that would slip past a casual review
  • Confirm a 3.0 document still validates after migrating it toward 3.1
  • Lint a contributor's OpenAPI changes in a PR without setting up a full validation toolchain

Frequently asked questions

Which OpenAPI versions are supported?

Both 3.0 and 3.1 documents are validated against the core spec rules for those versions.

What input formats does it take?

JSON or YAML, pasted as application/json, application/yaml, text/yaml, or plain text. It returns a JSON report.

What's the difference between normal and strict mode?

Normal mode catches structural errors that violate the spec. Strict mode additionally flags lints like missing operationIds and descriptions that aren't errors but are good practice.

Is my API spec uploaded to a server?

No. Validation runs in your browser, which matters since specs often describe internal endpoints you'd rather not send anywhere.

Why doesn't it bundle the full meta-schema?

It checks the common, high-value rules directly instead of shipping the 50 KB meta-schema, keeping it fast while still catching the errors that actually break tooling.

Keywords

  • openapi
  • swagger
  • api
  • validate
  • lint
  • spec

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