JSON Schema Validation: The Definitive Guide

What Is JSON Schema? JSON Schema is a declarative language for defining the structure, content, and constraints of JSON data. Think of it as a blueprint that describes what valid JSON looks like for your application. It is used for API request/response validation, form generation, configuration file validation, and documentation. Your First JSON Schema Suppose you have a user object: { "name" : "Alice" , "email" : "alice@example.com" , "age" : 30 } Here is a JSON Schema that validates this structure: { "$schema" : "https://json-schema.org/draft/2020-12/schema" , "title" : "User" , "description" : "A registered user in the system" , "type" : "object" , "properties" : { "name" : { "type" : "string" , "minLength" : 1 , "maxLength" : 100 }, "email" : { "type" : "string" , "format" : "email" }, "age" : { "type" : "integer" , "minimum" : 0 , "maximum" : 150 } }, "required" : [ "name" , "email" ], "additionalProperties" : false } Core Schema Types JSON Schema supports these primitive types: T