OpenAPI Validator Online — Schema Conformance Check
Check OpenAPI 3.0–3.2 schema conformance locally. JSON and YAML — external $ref are never fetched.
Developer notes
• Uses @scalar/openapi-parser via dynamic import (validate only). • Supports OpenAPI 3.0, 3.1, and 3.2. • External / URL $ref are never fetched. • Internal #/… references are checked by Scalar validate (broken refs fail). • Swagger 2.0 is rejected with a clear message. • Max input 512 KiB.
Use cases
• Catch missing info, invalid openapi versions, and schema errors before CI. • Paste a single-file spec (JSON or YAML) for a quick local check. • Confirm internal $ref targets resolve.
Examples
Valid minimal spec
Before
After
Swagger 2 rejected
Before
After
Validate OpenAPI FAQ
Common questions
What does validate check?
Schema conformance for OpenAPI 3.0–3.2 via @scalar/openapi-parser. It is not a style linter — use Lint OpenAPI for that.
Are $ref supported?
External and URL $ref are never fetched. Internal #/… references are checked: missing targets fail validation.
Is Swagger 2.0 supported?
No. Documents with a swagger key are rejected with a clear message. These pages do not claim Swagger validation.
JSON and YAML?
Both. Auto-detect with BOM strip; if a {…} document fails as JSON, YAML flow fallback is tried.
Related tools?
See also JSON Validator, Beautify YAML, and the API tools hub.
OpenAPI cluster tools
Looking for converters, encoders, formatters, and minifiers in one place? Developer tools hub Open the curated developer tools catalogue.