JSON Schema Validator

JSON Schema is a powerful vocabulary for annotating and validating JSON documents. It provides a clear, human- and machine-readable description of the structure, constraints, and semantics of JSON data. Originally proposed as an Internet Draft, JSON Schema has become the industry standard for API contract definition, configuration validation, and data interchange specification.

Core Validation Keywords

This validator supports the most commonly used JSON Schema keywords. The type keyword constrains the data type (string, number, integer, boolean, object, array, null). The properties keyword defines per-property schemas for objects, while required lists properties that must be present. The items keyword defines the schema for array elements. The enum keyword restricts a value to a fixed set of options.

Numeric Constraints

For numeric values, JSON Schema provides minimum, maximum, exclusiveMinimum, and exclusiveMaximum keywords to define valid ranges. The multipleOf keyword ensures a number is a multiple of a given value. These constraints are essential for validating API parameters, configuration thresholds, and data integrity checks. This tool evaluates all numeric constraints and reports precise error paths when violations occur.

String Constraints

String validation includes minLength and maxLength for length bounds, pattern for regular expression matching, and format for semantic validation. Supported format values include email, uri, date, date-time, ipv4, ipv6, and uuid. Pattern validation uses JavaScript regular expressions, making it easy to enforce complex string formats like phone numbers, postal codes, or custom identifiers.

Array and Object Constraints

Arrays support minItems, maxItems, and uniqueItems constraints. The items keyword defines the schema that each array element must conform to. Objects support minProperties, maxProperties, and additionalProperties (which can be a boolean or a schema). These keywords allow you to precisely define the shape and size of complex data structures.

Auto-Generate Schema from JSON

This tool includes a schema auto-generator that analyzes your JSON data and produces a basic JSON Schema. It infers types from values, detects required properties (all present keys are marked required), recognizes array item types, and sets appropriate constraints based on the data. The generated schema serves as a starting point that you can customize to add specific validation rules, optional properties, or additional constraints.

Use Cases for JSON Schema

JSON Schema is widely used across the software industry. API providers use it to define request and response contracts in OpenAPI (Swagger) specifications. Configuration management tools use it to validate YAML and JSON config files. Form builders use it to dynamically generate and validate web forms. Database schemas, message queue contracts, and CI/CD pipeline configurations all benefit from JSON Schema validation. This tool helps developers quickly test and iterate on their schemas.

100% Client-Side Processing

All validation in this tool happens entirely in your browser using a custom JavaScript JSON Schema validator. No data is transmitted to any server. Your JSON data, schemas, and validation results never leave your device, making this tool safe to use with production data, API contracts, and confidential configurations.