OpenAPI Spec Validator
Validate OpenAPI 2.0 (Swagger) and OpenAPI 3.0/3.1 specification files for compliance, missing required fields, unresolved $ref paths, and schema errors. Paste JSON or YAML or upload a file — errors and warnings are listed by path with severity levels and actionable fix suggestions. All validation runs entirely in your browser.
How to Use OpenAPI Spec Validator
How to Use the OpenAPI Spec Validator
Step 1: Paste or Upload Your Spec
Paste your OpenAPI or Swagger specification directly into the textarea, or click Upload to load a .json, .yaml, or .yml file from your computer. Both JSON and YAML formats are fully supported.
Step 2: Load an Example (optional)
Click one of the example buttons to load a pre-built spec:
- Minimal 3.0 — the smallest valid OpenAPI 3.0 spec
- Petstore 3.0 — a complete API with schemas, parameters, and request bodies
- Swagger 2.0 — a Swagger 2.0 spec with definitions and path parameters
- With Errors — an intentionally broken spec showing common mistakes
Step 3: Click Validate Spec
Click Validate Spec to run validation. Results appear immediately in the right panel.
Step 4: Review the Status and Stats
The status card shows whether the spec is valid (green) or invalid (red). The stats grid shows the detected version (Swagger 2.0, OpenAPI 3.0, or 3.1), the number of paths, operations, and schemas defined, plus the total error and warning counts.
Step 5: Fix Issues
The Issues panel lists each error and warning with:
- Path — the JSON path inside the document where the issue was found (e.g.,
#/paths/users/get/responses) - Message — a plain-English description of the problem
- Fix suggestion — a specific action you can take to resolve it
Errors (red) indicate spec non-compliance. Warnings (amber) are best-practice recommendations that do not prevent the spec from being technically valid.
What the Validator Checks
- Version field —
openapi(3.x) orswagger(2.x) must be present at the root - info object —
titleandversionare required;descriptionis recommended - paths object — must be present; each path must start with
/ - Operations — each must have a
responsesobject with at least one entry - Parameters — must include
nameandinwith valid values; path parameters must match the URL template - $ref resolution — all internal
$refvalues must point to paths that exist in the document - Security — if root
securityis set, the corresponding scheme definitions must exist - Best practices —
operationId,summary/description,requestBodyfor POST/PUT/PATCH, and 2xx responses
Limitations
This is a structural validator based on the OpenAPI specification rules. It does not execute a full JSON Schema validation of property values, does not check external $ref URLs, and does not validate discriminator or oneOf/anyOf semantics. For full compliance testing, use the validator as a first pass and follow up with an official OpenAPI library in your build pipeline.
Frequently Asked Questions
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