JSON Schema Validator

JSON Schema is a vocabulary that defines the structure, constraints, and documentation for JSON data. A JSON Schema specifies which properties an object must have (required fields), what types each property accepts (string, number, boolean, array, object), value constraints (minimum/maximum for numbers, minLength/maxLength for strings, pattern for regex validation), array rules (minItems, maxItems, uniqueItems, item type constraints), and conditional logic (if/then/else, oneOf, anyOf, allOf for complex validation). JSON Schema is used extensively in API contract validation — OpenAPI/Swagger specifications define request and response schemas that both producers and consumers can validate against. Form validation systems like React JSON Schema Form generate UI forms directly from schemas. Configuration file validation ensures that application settings conform to expected structures before deployment. The AllTools JSON Schema Validator takes a JSON document and a JSON Schema, then reports whether the document conforms to the schema, listing all validation errors with their JSON paths and descriptions. All validation happens in the browser using the Ajv library — your data and schemas stay on your device, important when validating proprietary API contracts or configurations containing sensitive infrastructure details.

JSON Schema serves as a contract between API producers and consumers, ensuring both sides agree on the data format. API documentation platforms like Swagger UI and Redoc render schemas as interactive documentation that developers can explore. API gateway services validate incoming requests against schemas, rejecting malformed requests before they reach the application. Client-side SDKs use schemas to generate type-safe client code. Testing frameworks validate API responses against schemas to detect breaking changes in CI/CD pipelines. The schema evolution process — adding optional fields, deprecating old fields, changing field types — requires careful version management to avoid breaking existing clients. Tools like JSON Schema $ref enable modular schema design where common definitions (an Address schema, a User schema) are defined once and referenced across multiple API endpoints. Draft versions of JSON Schema (Draft-04, Draft-06, Draft-07, Draft 2019-09, Draft 2020-12) have evolved the specification — the AllTools validator supports the most commonly used drafts. Understanding which draft your API uses ensures validation accuracy.