OpenAPI / Swagger Validator

OpenAPI (formerly known as Swagger) is the industry-standard specification for describing RESTful APIs. An OpenAPI spec defines your API's endpoints, request/response schemas, authentication methods, and more in a machine-readable format (YAML or JSON). Validation ensures your spec is structurally correct, references valid schemas, and follows best practices.

A malformed OpenAPI spec can cause code generation failures, broken API documentation, and integration issues. Common problems include missing required fields (like info or responses), broken $ref references to schemas that don't exist, missing operation IDs, and undocumented endpoints. Catching these issues early saves hours of debugging downstream.

Our OpenAPI validator accepts both YAML and JSON specs, validates them against the OpenAPI 3.0 structure, and provides a visual breakdown of your API. See all endpoints organized by HTTP method, inspect schemas and their properties, and review validation issues ranked by severity — all processed entirely in your browser with no server uploads.

1. Paste your spec — Copy your OpenAPI specification in YAML or JSON format into the input field. The tool auto-detects the format.
2. Click "Validate & Visualize" — The tool parses your spec, checks for structural errors, validates schema references, and analyzes all endpoints.
3. Review issues — Browse errors (missing required fields, broken references) and warnings (missing descriptions, unused schemas, missing tags) with exact paths to each problem.
4. Explore endpoints — Switch to the Endpoints tab to see all API routes organized by HTTP method. Click any endpoint to expand details including parameters, request bodies, and response codes.
5. Inspect schemas — View all defined schemas, their properties, and whether each schema is actually referenced by an endpoint or is unused dead code.

• YAML and JSON support — Paste your spec in either format. The built-in YAML parser handles standard OpenAPI YAML syntax without external dependencies.
• Structural validation — Checks for required fields (openapi version, info, title, paths, responses), validates $ref references, and detects broken schema links.
• Endpoint visualization — Color-coded HTTP methods (GET, POST, PUT, DELETE, PATCH) with expandable details showing parameters, request bodies, response codes, and operation IDs.
• Schema analysis — Lists all component schemas with their properties and flags unused schemas that aren't referenced by any endpoint.
• Stats dashboard — At-a-glance view of total endpoints, HTTP method breakdown, schema count, and overall valid/invalid status.
• 100% client-side — Your API spec never leaves your browser. No uploads, no server processing, no data retention.

• Pre-commit validation — Validate your OpenAPI spec before committing to catch missing fields, broken references, and incomplete documentation early.
• API documentation review — Check that all endpoints have summaries, descriptions, operation IDs, and tags before publishing API docs.
• Schema reference auditing — Find unused schemas cluttering your spec and verify that all $ref references point to existing component schemas.
• Code generation prep — Ensure your spec is valid before running code generators (openapi-generator, swagger-codegen) to avoid cryptic generation errors.
• API design review — Use the endpoint visualization to get a quick overview of your API surface area, HTTP method distribution, and response patterns during design reviews.