JSON Schema is a vocabulary that allows you to annotate and validate JSON documents. It defines the structure, data types, and constraints that your JSON data must follow.

What JSON Schema drafts are supported?

This validator supports JSON Schema Draft 4, Draft 6, Draft 7, and Draft 2020-12. It automatically detects the draft version from your schema's $schema keyword.

What is the difference between JSON Schema Draft 7 and Draft 2020-12?

Draft 2020-12 introduces prefixItems for tuple validation, $dynamicRef for dynamic references, and removes definitions in favor of $defs. It also has improved vocabularies and better support for conditional validation.

How do I use required fields in JSON Schema?

Add a 'required' array at the object level containing the names of properties that must be present. For example: { 'type': 'object', 'required': ['name', 'email'], 'properties': {...} }

Can I validate nested JSON objects with JSON Schema?

Yes, JSON Schema supports nested object validation. Define nested schemas within the 'properties' of parent objects, or use '$ref' to reference reusable schema definitions.

How do I validate array items in JSON Schema?

Use the 'items' keyword to define the schema for array elements. You can also use 'minItems', 'maxItems', and 'uniqueItems' to add additional constraints on the array.

What is the $ref keyword in JSON Schema?

The $ref keyword allows you to reference other schemas, either within the same document using JSON Pointer (e.g., '#/$defs/address') or external schemas via URI. This enables schema reuse and modular design.

How do I validate email format in JSON Schema?

Use the 'format' keyword with 'email' value: { 'type': 'string', 'format': 'email' }. Other supported formats include 'uri', 'date', 'date-time', 'uuid', 'ipv4', and 'ipv6'.

JSON Schema Validator Online - Validate JSON Free

Free online tool to validate your JSON data against a JSON Schema definition. Supports Draft 4, 7, and 2020-12.

📊 Results

Click Validate to check your JSON against the schema.

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What is JSON Schema?

JSON Schema is a declarative language for defining the structure and constraints of JSON data. It acts as a contract between systems, specifying what properties are allowed, their data types, required fields, and acceptable value ranges.

Developers use JSON Schema primarily for three purposes: validating API request and response payloads, enforcing configuration file formats, and documenting data structures in a machine-readable way. When you define a schema, any JSON document can be checked against it to ensure compliance before processing.

The schema itself is written in JSON, making it easy to parse, generate, and integrate into existing toolchains. Common keywords include type, properties, required, minimum, maximum, pattern, and format.

JSON Schema Validation Examples

Below is a simple schema that requires a name (string) and age (integer, minimum 0).

Schema Definition

{
  "type": "object",
  "required": ["name", "age"],
  "properties": {
    "name": { "type": "string", "minLength": 1 },
    "age": { "type": "integer", "minimum": 0 }
  }
}

✓ Valid JSON

{
  "name": "Alice",
  "age": 28
}

This passes because both required fields are present with correct types and age meets the minimum constraint.

✗ Invalid JSON

{
  "name": "Bob",
  "age": -5
}

This fails validation because age is below the minimum value of 0 defined in the schema.

JSON Schema Validator FAQs

Is this JSON Schema validator free to use?

Yes, this tool is completely free with no registration required. You can validate as many schemas as needed without any usage limits or hidden costs.

Is my JSON data secure when validating schemas?

All validation happens locally in your browser. Your JSON data never leaves your machine or gets transmitted to any server, ensuring complete privacy.

Can I validate large JSON Schema files?

The validator handles reasonably large schemas and JSON documents efficiently. For extremely large files, performance depends on your browser's memory and processing capabilities.

What JSON Schema versions are supported?

This validator supports Draft 4, Draft 6, Draft 7, and Draft 2020-12. The version is auto-detected from the $schema keyword in your schema definition.

What errors can a JSON Schema validator detect?

It detects type mismatches, missing required properties, values outside defined ranges, pattern violations, invalid formats, and structural issues like incorrect nesting or array constraints.

How do I validate JSON against a schema online?

Paste your JSON data in the JSON Data tab, switch to the Schema tab and paste your schema, then click Validate. Results appear instantly in the panel on the right.