What is JSON Schema?
JSON Schema is a standard for describing the expected structure of a JSON document. Think of it as a type system for your data: it defines which fields should exist, what type each field should be, and which fields are required. When data arrives at your API, you check it against the schema — and reject anything that doesn't match before it reaches your application logic.
{"type":"object","properties":{"id":{"type":"integer"},"name":{"type":"string"}},"required":["id","name"]}Why use JSON Schema?
Without schema validation, a missing required field causes an error deep inside your application logic — sometimes hours after the bad data arrived. With schema validation, the problem is caught immediately at the boundary where data enters your system, with a clear error message pointing to the exact field that's wrong.
Generate a schema from a sample automatically
You don't have to write schemas by hand. Paste a real JSON response or data sample into our JSON Schema Generator and it produces a draft-07 schema with correct types and required fields in seconds.
Validate data against a schema
Once you have a schema, use our JSON Schema Validator to check any JSON document against it. Every violation is reported with its exact path in the document, so you know precisely what needs to be fixed.
From schema to TypeScript
If you're working with TypeScript, our JSON to TypeScript tool generates matching interfaces from the same JSON sample, giving you type safety at compile time to complement the schema validation at runtime.
Frequently Asked Questions
- What JSON Schema version should I use?
- Draft-07 is the most widely supported version and covers all common use cases. Our tools generate draft-07 schemas. Draft 2019-09 and 2020-12 add features mainly relevant to advanced validation scenarios.
- Can JSON Schema validate nested objects?
- Yes — JSON Schema fully supports nested validation. You can define schemas for nested objects using
properties, create reusable definitions, and useanyOforoneOffor values that can have more than one valid shape. - Is JSON Schema only useful for APIs?
- Not at all. JSON Schema is equally useful for validating configuration files, database documents, form submissions, and any other structured data your application handles.