OpenAPI Validator Online — Schema Conformance Check

Check OpenAPI 3.0–3.2 schema conformance locally. JSON and YAML — external $ref are never fetched.

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Check OpenAPI 3.x schema conformance locally.

Developer notes

Uses @scalar/openapi-parser via dynamic import (validate only). Supports OpenAPI 3.0, 3.1, and 3.2. Live debounced validation; Monaco input with JSON/YAML auto-detect. 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. Results panel shows verdict, Scalar issue paths, and spec stats.

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

{ "openapi": "3.1.0", "info": { "title": "Pets", "version": "1.0.0" }, "paths": { "/pets": { "get": { "operationId": "listPets", "tags": ["pets"], "summary": "List pets", "responses": { "200": { "description": "OK" } } } } } }

After

Status: valid

Swagger 2 rejected

Before

{"swagger":"2.0","info":{"title":"t","version":"1"},"paths":{}}

After

Unsupported: Swagger 2.0

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.

API & schemas

OpenAPI tools to format, validate, and lint your specs.

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