Test API contracts
Validate request or response examples before integrating them into application code.
100% local · files never leave your browser
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JSON Schema Validator
Validate JSON data against JSON Schema in your browser using AJV. Check required fields, types and constraints privately.
✓ Free to use✓ No signup✓ Runs locally
33 bytes · local only
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Processed entirely in this tab
Your input and result are not sent to JSON Hearth or stored on a server.
When to use it
What Schema Validator helps you do
Schema validation checks whether a JSON value follows an explicit contract, including field types, required properties and supported constraints.
Check configuration files
Catch missing fields and invalid types before configuration reaches a runtime environment.
Develop a schema
Try valid and invalid fixtures while refining constraints and error messages.
How it works
Schema Validator, without the upload.
Add your data
Paste a value, open a local file or begin with the working sample.
Run the tool
The transformation executes in your browser, not on our servers.
Review the result
Check the output, then copy or download it for your next task.
Important limitations
What to check before using the result
Review required
Validation behaviour depends on the schema dialect and keywords supported by the validator configuration.
Review required
Passing a schema does not guarantee that business logic or external dependencies will accept the data.
Common questions
About Schema Validator
Does JSON Schema Validator upload my data?
No. Your input is processed by code running in your browser and is not sent to an application server.
Is Schema Validator free to use?
Yes. The tool is free, requires no account and can be used directly in the browser.
How is schema validation different from syntax validation?
Syntax validation checks whether text is JSON. Schema validation also checks the parsed value against declared rules.
Why can valid JSON fail a JSON Schema?
The document may parse correctly but still have missing properties, incorrect types or values outside schema constraints.