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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

What is a JSON schema?

A JSON schema is a document that describes the structure, types, and constraints of JSON data. It defines what properties should exist, their data types, and any validation rules.

What validation rules are supported?

This validator supports type checking, required properties, minimum/maximum values, string patterns, email/URI/date formats, array item validation, object nesting, and more.

Can I validate nested objects?

Yes, the validator recursively checks nested objects and arrays. You can define schemas for properties at any depth in your JSON structure.

What format validations are available?

Supported formats include email (user@example.com), uri (https://example.com), and date (YYYY-MM-DD). Other formats can be validated using regex patterns.

How do I require certain properties?

Add a "required" array in your schema with the names of properties that must be present in the JSON object. If a required property is missing, validation fails.

Can I restrict to specific enum values?

Yes, use the "enum" property in your schema to restrict a value to one of a predefined set of options. For example, status can only be "active", "inactive", or "pending".

What about array validation?

Use "type": "array" and define the "items" schema for array elements. You can set minItems, maxItems to control array length and validate each element against the schema.

How do I prevent extra properties?

Set "additionalProperties": false in your schema. This makes the validator reject any properties not explicitly defined in the properties list.

Is this compliant with JSON Schema standard?

This validator implements common JSON Schema features (Draft 7 style). For advanced features or full JSON Schema compliance, consider using dedicated libraries like Ajv.

Is my data private?

Yes, all validation happens entirely in your browser. Your JSON data and schemas are never sent to any server and are not stored or logged.

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