Data formatters
JSON Schema Validator
Validate JSON against a practical JSON Schema subset locally in your browser.
How to use this tool
Paste the JSON document you want to validate.
Paste a JSON Schema that describes the expected object shape, required fields, types, arrays, and value limits.
Review the validation errors and fix the data or schema before using the JSON in production.
When JSON Schema is useful
JSON Schema is useful when APIs, config files, automation payloads, or exported data need a predictable structure.
A schema can catch missing required fields, wrong primitive types, unexpected properties, invalid enum values, and malformed arrays.
For teams, a schema also becomes lightweight documentation that machines can check automatically.
Supported validation rules
This browser validator covers a practical subset of JSON Schema: `type`, `required`, `properties`, `additionalProperties`, `items`, `enum`, `const`, string length, numeric limits, array limits, and patterns.
It is designed for quick checks and documentation examples, not as a full replacement for a production validator in CI.
If your schema relies on advanced features such as `$ref`, conditionals, custom formats, or complex composition, test it with your production validation library too.
Examples
Required field validation
Input{"name":"Lumio","tools":61}Output{"type":"object","required":["name","tools"],"properties":{"name":{"type":"string"},"tools":{"type":"number"}}}Unexpected property check
Set `additionalProperties` to `false` when you want to reject fields that are not declared in the schema.
FAQ
Is this a complete JSON Schema implementation?
No. It supports a practical browser-side subset for quick validation. Advanced schema features should be checked with a full JSON Schema library.
Can I validate API responses here?
Yes, paste a sample response and the matching schema. Do not paste secrets, tokens, or private customer data into any browser tool unless you are comfortable handling it locally.
What does additionalProperties false do?
It rejects object fields that are not listed in the schema properties map.
Is my JSON uploaded?
No. Validation runs locally in your browser.