JSON Schema Validator
What Is It?
The JSON Schema Validator validates any JSON document against a JSON Schema (Draft-07). Paste your data and schema, then click Validate to instantly see if your JSON is valid — with precise, field-level error messages showing exactly where and why validation failed.
Everything runs in your browser. No data is ever uploaded.
How to Use
- Paste your JSON data into the left panel.
- Paste your JSON Schema into the right panel.
- Click Validate JSON.
- See a green ✓ Valid badge if successful, or red error messages with paths if validation fails.
- Click Load Example to see a quick demo.
Supported JSON Schema Keywords (Draft-07)
| Category | Keywords |
|---|---|
| Types | type, enum, const |
| Strings | minLength, maxLength, pattern, format (email, uri) |
| Numbers | minimum, maximum, exclusiveMinimum, exclusiveMaximum, multipleOf |
| Arrays | items, minItems, maxItems, uniqueItems |
| Objects | properties, required, additionalProperties, minProperties, maxProperties |
| Logic | allOf, anyOf, oneOf, not, if/then/else |
Example Schema
{
"type": "object",
"required": ["name", "age"],
"properties": {
"name": { "type": "string", "minLength": 1 },
"age": { "type": "integer", "minimum": 0 },
"email": { "type": "string", "format": "email" }
}
}
Benefits
- Field-level errors — errors show the exact JSON path (e.g.,
#.age) where validation failed. - No external libraries — the validator is built in pure JavaScript, zero dependencies.
- Draft-07 coverage — supports all major JSON Schema keywords.
- Instant feedback — validation runs in milliseconds in the browser.
- 100% private — your JSON data never leaves your machine.
Common Use Cases
- Testing API request and response payloads against a defined schema.
- Validating configuration files before deployment.
- Checking generated JSON against an OpenAPI schema definition.
- Debugging form submission data structures in web applications.
- Teaching JSON Schema concepts with immediate, live validation feedback.
Frequently Asked Questions
What is JSON Schema?
JSON Schema is a vocabulary that allows you to annotate and validate JSON documents. A schema defines the expected structure, data types, and constraints for a valid JSON payload. It is widely used in API development, configuration management, and data validation.
Which JSON Schema version does this tool support?
This tool implements JSON Schema Draft-07, which is one of the most widely adopted versions and forms the basis for many API specifications, including OpenAPI 3.0.
What does a validation error path mean?
Errors are shown with a path like #.user.age. The # symbol represents the root of the JSON document, and each .property or [index] indicates a nested key or array index where the error occurred.
Can I validate arrays with this tool?
Yes. If your root JSON value is an array, define the top-level schema type as "array" and use the "items" keyword to define constraints for each element.
Is additionalProperties: false supported?
Yes. Setting additionalProperties: false in your schema will cause validation to fail if the JSON data contains any property not listed under properties.
