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OpenAPI & Swagger Validator
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OpenAPI & Swagger Validator

Validate OpenAPI 3.x and Swagger 2.0 documents online — structural checks, $ref resolution, endpoint listing and stats. JSON or YAML, paste or fetch — free, no signup.

Valid OpenAPI 3.0.3 document Pet API · API v1.2.0
2paths
3operations
1schemas
0external $refs

Endpoints

GET/petslistPets
POST/petscreatePet
GET/pets/{petId}getPet

No issues found — structure, references and operations all check out.

About OpenAPI & Swagger Validator

Paste an OpenAPI 3.x or Swagger 2.0 document (JSON or YAML) — or fetch it from a URL — and get a structural report: required sections, path/operation/response shapes, path-template parameters, duplicate operationIds, undeclared tags and local $refs that don't resolve.

The summary panel doubles as a quick spec viewer: dialect and version, endpoint list with methods and operationIds, and path/operation/schema counts. Structural issues are listed with their location so they're easy to fix. Validation runs locally; only URL fetching goes through our server.