Chapter 8: JSON Schema - Interactive JSON Tutorial

What is JSON Schema?

JSON Schema is a declarative format for validating the structure, types, and constraints of JSON data. It acts as a "blueprint" or "rulebook" for JSON data.

💡 Uses: API validation, config file checking, data formatting, auto-generated documentation

Schema Example

Defining a Schema for a user object:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "name": {
      "type": "string",
      "minLength": 2,
      "maxLength": 50
    },
    "age": {
      "type": "integer",
      "minimum": 0,
      "maximum": 150
    },
    "email": {
      "type": "string",
      "format": "email"
    }
  },
  "required": ["name", "age"],
  "additionalProperties": false
}

✅ Valid Data

{"name": "John Doe", "age": 30, "email": "john@example.com"}

❌ Invalid Data

{"name": "Jane Smith"} (missing age)

Common Keywords

Type Constraints

type : Data Type
enum : Enum Values

Numeric Constraints

minimum/maximum : Min/Max
exclusiveMinimum : Exclusive Minimum

String Constraints

minLength/maxLength : Length
pattern : Regex Pattern
format : Predefined Format

Array Constraints

items : Item Type
minItems/maxItems : Count
uniqueItems : Uniqueness