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JSON Schema Validator

What Is a JSON Schema Validator?

A JSON Schema validator checks whether JSON data follows the rules defined in a JSON Schema. A schema describes what your data should look like: required fields, data types, allowed values, formats, and number limits. A basic JSON validator only checks syntax, while a schema validator checks the structure and content of your data.

ToolsViewer's online JSON Schema validator has three panes: your JSON, your schema, and the result. It lists every place the data breaks the schema, along with the path and the reason.

How to Use the JSON Schema Validator

Step 1: Add your JSON data
Paste or import the JSON you want to check. Loading the sample fills in both a document and a schema.

Step 2: Add your schema
Paste or edit your JSON Schema in the schema pane. It is saved in your browser for next time.

Step 3: Click Validate
The tool checks your data against the schema.

Step 4: Read the result
The Result pane shows whether the data is valid and lists any errors with their paths and messages. Fix the data or the schema and validate again.

JSON Schema Validator Features

  • Validate JSON data against a JSON Schema
  • Version detection from $schema: Draft 4, Draft 7, 2019-09, and 2020-12 (2020-12 by default)
  • Reports all errors, not just the first one
  • Checks types, required fields, formats, enums, number limits, and more
  • Detailed errors with the instance path, schema path, message, and keyword
  • Three-pane layout: JSON, Schema, and Result
  • Schema saved in your browser
  • Sample, Import JSON, Validate, and Download result options
  • Send the document and schema to related tools
  • Private processing in your browser

Common Uses

Test API contracts: Confirm that responses match the documented schema.

Validate incoming data: Check payloads before your application processes them.

Build and debug schemas: Test a schema against valid and invalid samples.

Check configuration files: Make sure settings follow the required structure.

Find every problem at once: See all failures in one run instead of fixing them one by one.

Supported Formats

  • JSON data as text or .json files
  • JSON Schema as text
  • Output as a JSON result

This tool does not check basic syntax on its own. For that, use JSON Validator. A few rarely used schema features may not be supported.

Explore related tools like JSON Validator, JSON to TypeScript, and JSON Diff Checker to validate, convert, and compare JSON online.