How to use the JSON Schema Validator
Validate JSON against a schema:
1
Paste your JSON Schema
Add your JSON Schema definition to the left panel. Use the '✓ Valid Example' or '✗ Invalid Example' buttons to load a working sample schema instantly.
2
Paste your JSON data
Add the JSON data you want to validate to the right panel. The data panel border turns green on pass and red on fail for instant visual feedback.
3
Click Validate
See instant pass/fail results. Each error shows the JSON path that failed (e.g. #/address/zip), the failing keyword (e.g. pattern), and a human-readable error message.
4
Fix and re-validate
Fix the issues in either the schema or the data — editing either panel resets the result automatically. Click Validate again to confirm the fix.
When to use this tool
Use this to check JSON data against a schema definition:
- →Testing that an API response matches your documented JSON Schema definition
- →Debugging schema validation errors by testing schema and data side by side
- →Validating JSON config files against a published schema before deployment
- →Checking that your JSON Schema is correctly written by testing it against both valid and invalid sample data
- →Learning JSON Schema by experimenting with keywords like anyOf, oneOf, and if/then/else interactively
Frequently asked questions
Q:Which JSON Schema draft is supported?
The validator supports JSON Schema Draft-07 keywords, which is the most widely used version and compatible with the majority of published schemas. Supported keywords include type, required, properties, enum, const, format, pattern, minimum, maximum, items, uniqueItems, allOf, anyOf, oneOf, not, if/then/else, and additionalProperties.
Q:What do the error paths mean?
Error paths like #/address/zip show exactly which nested property failed validation using JSON Pointer notation (RFC 6901). The # represents the root of the document, and each segment after / is a key or array index. This makes it easy to pinpoint failures in deeply nested data structures.
Q:What format values are supported?
The validator supports the following format keywords: email (valid email address), uri and url (valid URL), date (YYYY-MM-DD), date-time (ISO 8601 datetime), uuid (standard UUID format), and ipv4 (valid IPv4 address). Unknown format values are ignored rather than causing errors.
Q:What is the difference between allOf, anyOf, and oneOf?
allOf means the data must be valid against all listed subschemas. anyOf means it must be valid against at least one. oneOf means it must be valid against exactly one — if it matches more than one, validation fails. These are used to compose complex schemas from simpler building blocks.
Q:What does additionalProperties: false do?
When additionalProperties is set to false, any property in the JSON data that is not listed in the properties keyword causes a validation error. This is useful for strict API contracts where unexpected fields should be rejected.
Q:Is my data sent to a server?
No — all validation runs entirely in your browser using a built-in JavaScript validation engine. Your schema and JSON data never leave your device and are never stored or logged.