JSON Schema

Quick Start

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "required": ["id", "name"],
  "properties": {
    "id": { "type": "integer", "minimum": 1 },
    "name": { "type": "string", "minLength": 1 },
    "email": { "type": "string", "format": "email" },
    "tags": {
      "type": "array",
      "items": { "type": "string" },
      "uniqueItems": true
    }
  },
  "additionalProperties": false
}

Core Keywords

• Types: string, number, integer, boolean, array, object, null
• String: minLength, maxLength, pattern, format
• Number: minimum, maximum, exclusiveMinimum, exclusiveMaximum, multipleOf
• Array: items, minItems, maxItems, uniqueItems, contains
• Object: properties, required, additionalProperties, patternProperties
• Composition: allOf, anyOf, oneOf, not
• Conditional: if/then/else
• References: $ref, $defs (or definitions in draft-07)

Common Formats

date-time, date, time, email, uri, uuid, ipv4, ipv6, regex

Ajv (JavaScript Validator)

import Ajv from 'ajv';
import addFormats from 'ajv-formats';

const ajv = new Ajv({ allErrors: true });
addFormats(ajv);

const validate = ajv.compile(schema);
if (!validate(data)) console.log(validate.errors);

Reference Files

• references/keywords.md - Complete keyword reference
• references/composition.md - allOf/anyOf/oneOf patterns
• references/ajv.md - Ajv configuration and usage