Does it support Swagger 2.0?

Yes, both OpenAPI 3.x and Swagger 2.0 documents are recognized and validated.

Does it support YAML input?

Yes, paste either JSON or YAML — the tool auto-detects the format.

Does it validate external $refs?

Only local #/ references are resolved and checked; external file or URL refs are flagged as unverified.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

OpenAPI / Swagger Validator

Validate OpenAPI 3.x / Swagger 2.0 documents in JSON or YAML.

Support

Works Offline

Privacy First

No Login

No API

OpenAPI / Swagger document (JSON or YAML)

Validation results

Spec version

3.0.0

Endpoints

Format

OpenAPI 3.x

Errors

Warnings

errorOperation 'GET /users/{id}' is missing a 'responses' object.
errorDuplicate operationId 'listUsers' used 2 times.
warningOperation 'GET /users' has no summary or description.
warningOperation 'GET /users/{id}' has no summary or description.

About the OpenAPI / Swagger Validator

Paste an OpenAPI 3.x or Swagger 2.0 document as JSON or YAML to check required root fields, path operations, missing responses, duplicate operationIds, and unresolved $refs, with a summary of endpoints and severity-tagged issues.

Examples

Missing responses

{"openapi":"3.0.0","info":{"title":"A","version":"1"},"paths":{"/x":{"get":{}}}}

Output

Error: Operation 'GET /x' is missing a 'responses' object.

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-10 · Runs entirely in your browser