Validate JSON Online
Validate JSON against a schema in your browser — Draft 7, 2019-09, 2020-12◀ Schema
JSON ▶
JSON Schema
Schema draft
Load sample
AdvertisementResponsive
JSON to validate
About Validate JSON Online
Paste a JSON Schema on the left and your JSON data on the right. The validator checks your JSON against the schema in real time and lists every error with its path and message. Supports JSON Schema Draft 7, Draft 2019-09, and Draft 2020-12 via the AJV library. Three preset sample schemas included: Person, Product, and API Response. All validation runs in your browser — your data never leaves your device.
Frequently Asked Questions
What is JSON Schema validation?
JSON Schema validation checks that a JSON document conforms to a schema definition — verifying required fields are present, values match expected types, strings match patterns, and numbers fall within specified ranges. It enforces data contracts beyond simple syntax checking.
What JSON Schema draft versions are supported — Draft 7, 2019-09, 2020-12?
The validator supports Draft 7, Draft 2019-09, and Draft 2020-12. Draft 7 is the most widely compatible and is the right default. Select the draft that matches the $schema declaration in your schema file — using the wrong draft causes newer keywords like unevaluatedProperties or prefixItems to be silently ignored.
How do I write a JSON Schema to mark certain fields as required?
Add a required array alongside the properties object: {"type":"object","properties":{"name":{"type":"string"}},"required":["name"]}. Fields listed in required must be present in every validated document. Fields not listed are optional by default. The validator reports the exact path of any missing required field.
What is the difference between additionalProperties: false and strict validation?
additionalProperties: false makes any property not declared in properties an error. Without it, extra properties are silently allowed. This is the standard way to enforce strict API contracts. Note: the restriction applies only at the current object level — nested objects each need their own additionalProperties: false.
Can I validate a JSON Schema document against the meta-schema itself?
Yes. Paste the meta-schema as the Schema input and your JSON Schema document as the Data. The meta-schema URI is https://json-schema.org/draft/2020-12/schema for Draft 2020-12 (and equivalent URIs for other drafts). This validates that your schema is correctly structured — useful when generating schemas programmatically.