Key Facts
- Category
- Security & Validation
- Input Types
- textarea
- Output Type
- html
- Sample Coverage
- 4
- API Ready
- Yes
Overview
The OpenAPI / Swagger Validator is a web-based utility designed to structurally validate OpenAPI 3.0/3.1 and Swagger 2.0 specifications. It checks for required fields, path and operation completeness, response codes, $ref resolution, operationId uniqueness, and component integrity to ensure your API documentation is accurate and compliant.
When to Use
- •When debugging API specification errors before generating client SDKs or server stubs.
- •When verifying that local OpenAPI 3.0/3.1 or Swagger 2.0 YAML/JSON files comply with official schema standards.
- •When checking for broken internal $ref references or duplicate operationId values in large API definitions.
How It Works
- •Paste your OpenAPI 3.0/3.1 or Swagger 2.0 document in YAML or JSON format into the input text area.
- •The validator parses the document structure, resolving internal and external $ref references.
- •The tool checks for schema compliance, including required fields, unique operation IDs, and valid response codes.
- •Review the generated HTML report detailing any structural errors, warnings, or validation successes.
Use Cases
Validating a newly written OpenAPI 3.0.3 YAML file before committing it to a Git repository.
Troubleshooting broken schema references ($ref) in a complex Swagger 2.0 JSON document.
Ensuring all API endpoints have defined response codes and unique operation IDs for SDK generation.
Examples
1. Resolving Broken Schema References
API Platform Engineer- Background
- An engineer is updating a microservice API contract and gets errors when generating client libraries due to unresolved references.
- Problem
- The API specification contains multiple nested $ref pointers, and some point to non-existent schemas in the components section.
- How to Use
- Paste the YAML specification into the input area and click validate to locate the exact line numbers of the broken $ref definitions.
- Example Config
-
openapi: 3.0.0 info: title: Broken Ref API version: 1.0.0 paths: /users: get: responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/UserNonExistent' - Outcome
- The validator flags the missing '#/components/schemas/UserNonExistent' reference, allowing the engineer to quickly define the missing schema.
2. Fixing Duplicate Operation IDs
Backend Developer- Background
- A developer is merging two API modules into a single Swagger 2.0 specification file.
- Problem
- The merged file contains duplicate operationId values, which will break the automated SDK generation pipeline.
- How to Use
- Paste the merged Swagger 2.0 JSON document into the validator text area.
- Example Config
-
{ "swagger": "2.0", "info": { "title": "Duplicate ID API", "version": "1.0.0" }, "paths": { "/items": { "get": { "operationId": "getItems", "responses": { "200": { "description": "Success" } } } }, "/products": { "get": { "operationId": "getItems", "responses": { "200": { "description": "Success" } } } } } } - Outcome
- The validator highlights the duplicate 'getItems' operationId, enabling the developer to rename it to 'getProducts' and pass validation.
Try with Samples
validationOpenAPI/Swagger Samples
OpenAPI/Swagger specification examples for REST API documentation and contract definition
title token openapi,swagger
OpenAPI/Swagger Samples
Comprehensive API documentation examples using OpenAPI 3.0 and Swagger specifications for RESTful services
title token openapi,swagger
Mock Service Worker Samples
Comprehensive MSW (Mock Service Worker) examples for API mocking, GraphQL, WebSocket mocking, and advanced request handling patterns
keywords api,rest
Postman Collections - API Testing
Comprehensive Postman collection examples including API testing, automation scripts, environment variables, mock servers, and advanced testing patterns for REST APIs
keywords api,rest
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FAQ
Which OpenAPI versions are supported?
The validator supports OpenAPI versions 3.0 and 3.1, as well as Swagger 2.0.
Can I validate both JSON and YAML formats?
Yes, the tool accepts both JSON and YAML formatted API specifications.
How does the tool handle $ref resolution?
It automatically resolves internal references to components and schemas to verify their integrity.
Why is operationId uniqueness important?
Duplicate operationIds cause code generation tools to fail or produce conflicting client SDK methods.
Does this tool store my API specifications?
No, all validation is performed locally in your browser, and your API data is not saved.