JSON Schema Validator
Validate JSON data against a JSON Schema. Check types, required fields, formats, and constraints instantly.
Features
- ✓Validate JSON data against a JSON Schema
- ✓Support for type, required, properties, items, enum, and more
- ✓Format validation for email, URI, date, and date-time
- ✓Detailed error messages with JSON paths
- ✓Load sample schema and data with one click
- ✓No server required — everything runs in your browser
How to Use
- 1Paste or write your JSON Schema in the left panel
- 2Paste or write your JSON data in the right panel
- 3Click "Validate" to check the data against the schema
- 4View results: green for valid, red with error details for invalid
- 5Use "Load Sample" to see an example schema and data
Examples
Input
Schema: { "type": "object", "properties": { "name": { "type": "string" }, "age": { "type": "integer", "minimum": 0 } }, "required": ["name"] }Output
✓ Valid — JSON matches the schema
Input
Schema requires "email" but data is { "name": "Alice" }Output
✗ Invalid — Missing required property "email" at root
Input
Schema expects "age" as integer but data has "age": "twenty"
Output
✗ Invalid — Expected type "integer" but got "string" at age
What is JSON Schema Validation?
JSON Schema is a vocabulary for annotating and validating the structure of JSON data. It defines what shape your JSON should have, including data types, required fields, value constraints, and nested structures. JSON Schema validation ensures that a piece of JSON data conforms to a predefined schema, catching errors before they cause problems in your application.
This validator supports the most common JSON Schema keywords that cover the vast majority of real-world use cases: type checking (string, number, integer, boolean, array, object, null), property definitions with required fields, array item validation, numeric constraints (minimum, maximum, exclusiveMinimum, exclusiveMaximum), string constraints (minLength, maxLength, pattern), enum values, and format validation for email, URI, date, and date-time.
JSON Schema validation is essential for API development. When you build a REST or GraphQL API, you need to validate incoming request bodies to prevent invalid data from reaching your business logic. By defining a schema for each endpoint, you create a clear contract between frontend and backend teams. The schema serves as both documentation and runtime validation.
Beyond APIs, JSON Schema is used for configuration file validation, form validation, data pipeline integrity checks, and database document validation (e.g., MongoDB schema validation). It is also the foundation for OpenAPI (Swagger) specifications, making it a critical tool for API-first development workflows.
Our validator processes everything client-side — your schema and data never leave your browser. It provides detailed error messages with JSON paths (like "root.address.zipCode") so you can quickly locate and fix issues. This makes it ideal for debugging schema definitions, testing validation rules, and learning how JSON Schema works.