JSON Schema Generator

About JSON Schema

JSON Schema is a vocabulary that allows you to annotate and validate JSON documents. It describes the structure of JSON data, including data types, required fields, and constraints.

Related: generate sample data to build a schema from with the JSON generator.

Benefits of JSON Schema

• Validation: Automatically validate JSON data against a schema
• Documentation: Self-documenting data structures
• Code Generation: Generate types for TypeScript, Java, etc.
• API Design: Define API request/response formats

Schema Keywords

• type: Data type (string, number, object, array, etc.)
• properties: Object property definitions
• required: List of required properties
• items: Schema for array items
• enum: Allowed values
• minimum/maximum: Number constraints
• minLength/maxLength: String length constraints

Example Schema

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "name": { "type": "string" },
    "age": { "type": "integer", "minimum": 0 }
  },
  "required": ["name"]
}

From Schema to Code

Generating a schema is just the start. The real power comes from using that schema to catch bugs before they hit production — validating API payloads, generating TypeScript types, or documenting exactly what shape your data should have.

JSONLint Schema Validator lets you test JSON against any schema with detailed error messages that point to exactly where validation failed.