Real-time validation of OpenAPI/Swagger document structure, field completeness, and reference validity with precise error location
Zero Dependencies · Works Offline📝 OpenAPI/Swagger Document Input
What Can the OpenAPI Validator Do?
The OpenAPI Validator is a free online developer tool that performs real-time validation of OpenAPI/Swagger API document specification compliance. It checks required fields, field types, reference path validity, HTTP method legality, status code format, Schema structure, and more, with precise error positioning. Supports OpenAPI 3.0/3.1 and Swagger 2.0 with automatic version detection. Ideal for API developers writing and debugging API documentation to ensure spec compliance. All validation happens locally in your browser — API document content is never uploaded to any server.
Core Features
- Auto Version Detection: Automatically identifies OpenAPI 3.0/3.1 and Swagger 2.0, applying corresponding validation rules
- Required Field Checks: Validates that openapi/info/paths and other required fields exist and are correctly formatted
- Reference Validity: Checks that $ref reference paths point to existing definitions in the document
- HTTP Method Validation: Verifies that HTTP methods under paths are valid (get/post/put/delete etc.)
- Schema Structure Checks: Validates Schema object type/properties/items field formats
How to Use
1. Paste your OpenAPI/Swagger document content into the input area (supports JSON and YAML formats).
2. Click "Validate" or press Ctrl+Enter to analyze the document immediately.
3. Review results: statistics show error/warning counts, detailed list shows issue locations.
4. Fix errors based on the messages, then re-validate until all checks pass.
5. Click "Copy Report" or "Download Report" to save validation results.
Use Cases
Case 1: API Documentation Writing
API developers validate spec compliance in real-time while writing OpenAPI docs, reducing errors and improving documentation quality.
Case 2: API Design Review
Teams use this tool to quickly check document spec compliance during API design reviews, ensuring design consistency.
Case 3: API Gateway Configuration
DevOps engineers validate OpenAPI document format before configuring API gateways (Kong, AWS API Gateway), avoiding import failures.
Extended Knowledge
The OpenAPI Specification (OAS, formerly Swagger Specification) is the REST API description standard, with current mainstream versions being 3.0.x and 3.1.x. OpenAPI 3.0 is based on JSON Schema draft-04, while 3.1 uses draft-2020-12. Core structure includes: openapi (version), info (metadata), servers (server list), paths (API paths), components (reusable components), security (security schemes), and tags (tag grouping). $ref references avoid duplicate definitions, formatted as #/components/schemas/XXX. Swagger 2.0 is the legacy spec with a slightly different structure (swagger field, definitions instead of components).
❓ FAQ
Does it support OpenAPI 3.0 and 3.1?
Yes. Supports OpenAPI 3.0.x, 3.1.x, and Swagger 2.0 with auto-detection and corresponding rules.
What does validation cover?
Required fields, field types, reference validity, HTTP methods, status codes, Schema structure, server URLs, and security scheme references.
Can it replace Spectral?
This tool provides basic structural validation for quick pre-checks. Spectral offers richer custom rules for CI/CD. Use both together.
Is my data safe?
Yes. All validation happens locally in your browser. API document content is never uploaded.
Does it support YAML and JSON?
Yes. Auto-detects input format without manual specification.
Can I drag and drop files?
Yes. Drag .yaml/.yml/.json files onto the input area to auto-load content.
How are $ref references validated?
The tool checks if $ref paths point to existing definitions in the document, e.g., #/components/schemas/User must have User defined in components.schemas.
Feedback: dexshuang@google.com