JSON Schema Validator
Validate your JSON data against a schema. Check types, formats, required properties, value constraints, and more.
JSON Data
JSON Schema
How to Validate JSON Against Schema
- Step 1: Enter Your JSON Data - Paste your JSON data into the "JSON Data" field. This is the data you want to validate. Click "Sample JSON" for an example.
- Step 2: Define or Paste Your Schema - Enter a JSON schema that describes the expected structure and constraints of your data. Click "Sample Schema" to see a common schema example.
- Step 3: Click Validate - Click the "Validate" button to check if your JSON data matches the schema definition.
- Step 4: Review Results - See validation results showing if the data is valid. Any errors are displayed with their locations and descriptions.
Understanding Schema Properties
- type: Data type (string, number, integer, boolean, array, object, null)
- properties: Define expected properties in an object
- required: List of property names that must be present
- minimum/maximum: Numeric range constraints
- minLength/maxLength: String length constraints
- format: Special formats like email, uri, date
Frequently Asked Questions
How do I validate JSON against schema online for free?
Paste your JSON data in one field and your JSON Schema in another field. Click "Validate" and the tool will check if your JSON conforms to the schema, showing detailed error messages for any validation failures including which properties failed and why.
What is JSON Schema validation?
JSON Schema validation checks if your JSON data matches a defined structure (schema). The schema specifies required properties, data types, formats, patterns, and constraints. This ensures data consistency, API contract compliance, and catches errors before they reach production.
Which JSON Schema draft versions are supported?
The validator supports JSON Schema Draft 7 (latest stable), Draft 6, and Draft 4. Draft 7 is recommended for new projects as it includes the latest features and improvements for data validation.
Can I validate API responses with this tool?
Yes! Paste your API response JSON and your API's JSON Schema specification. The validator will confirm if the response matches the expected schema, helping you catch API contract violations, missing fields, or incorrect data types during development and testing.
What happens when JSON Schema validation fails?
The validator shows detailed error messages indicating which properties failed validation, the expected vs actual data types, missing required fields, pattern mismatches, and the exact path to the problem in your JSON structure. This helps quickly identify and fix data issues.
How do I create a JSON Schema?
A JSON Schema defines the structure using properties like 'type' (string, number, object, array), 'required' (mandatory fields), 'properties' (object structure), 'items' (array contents), and constraints like 'minimum', 'maximum', 'pattern', etc. Start with a simple schema and add constraints as needed.
About JSON Schema Validation
Our JSON Schema Validator helps you validate JSON data against schemas to ensure data integrity, type safety, and structural correctness. All validation happens entirely in your browser for complete privacy.
JSON Schema is a powerful vocabulary for annotating and validating JSON documents. It's widely used in API development, data validation, and configuration management to ensure data conforms to expected formats.
Key Features
- Validate JSON against JSON Schema specifications (Draft 7 compatible)
- Type checking (string, number, integer, boolean, array, object, null)
- Required property validation
- Numeric constraints (minimum, maximum, multipleOf)
- String constraints (minLength, maxLength, pattern)
- Format validation (email, uri, date, time, hostname)
- Array validation (minItems, maxItems, uniqueItems)
- Nested object and array schema validation
- Enum value restrictions
- Detailed error messages with property paths
- 100% client-side processing for privacy
Common Schema Validations
API Request Validation
Validate incoming API requests match expected schema before processing. Catch invalid data early.
Configuration Files
Ensure config files (package.json, tsconfig, etc.) have correct structure and valid values.
Form Data Validation
Validate form submissions and user input against defined schemas for data quality.
Database Records
Verify database records match expected schema before insertion or updates.
Schema Validation Use Cases
- REST API Development: Define and validate request/response schemas
- GraphQL APIs: Validate query variables and input types
- Microservices: Ensure message contracts between services
- Data Import/Export: Validate data integrity during transfers
- Testing: Create test data that matches production schemas
- Documentation: Use schemas as self-documenting API contracts
- Code Generation: Generate TypeScript interfaces from schemas
- CI/CD Pipelines: Automate schema validation in deployment workflows
JSON Schema Best Practices
- Start Simple: Begin with basic type and required field validation
- Add Constraints Gradually: Layer on format, range, and pattern validation
- Use Descriptive Titles: Include title and description in schemas for clarity
- Version Your Schemas: Track schema changes over time for API evolution
- Reuse Definitions: Use $ref to reference common schema patterns
- Test Schemas: Validate both valid and invalid examples against schemas
- Document Formats: Clearly specify format expectations (email, uri, etc.)
Learn More About JSON Schema
JSON Schema is a vocabulary that allows you to annotate and validate JSON documents. It provides a contract for JSON data, defining what properties are required, what types are expected, and what validation rules apply.
JSON Schema Resources
- json-schema.org— Official JSON Schema documentation and specifications
- Understanding JSON Schema— Comprehensive guide to JSON Schema concepts
- AJV— Another JSON Schema Validator (JavaScript library)
- JSON Schema Store— Collection of schemas for common file formats