JSON Schema Validator is designed for the exact search intent behind “json schema validator”. Validate JSON instance data against a JSON Schema and review reported constraint errors. This is different from checking JSON syntax alone: the JSON can parse correctly and still fail the schema. Validate a JSON instance against a JSON Schema and diagnose schema constraint failures. What JSON Schema validation checks A schema can define expected data types, required object properties, array rules, numeric and string constraints, enumerated values and relationships between parts of a JSON document. The validator compares an instance against the constraints expressed by the supplied schema. How to use the validator Paste or enter the JSON instance. Provide the JSON Schema in the format supported by the tool. Run validation. Use the reported instance path, schema rule and message to locate mismatches. Valid JSON is not the same as schema-valid JSON {"age":"twenty"} can be perfectly valid JSON syntax. If the schema requires age to be an integer, however, that instance fails schema validation. JSON Schema drafts and dialects JSON Schema has evolved through multiple drafts. Supported keywords, vocabularies and format behavior depend on the validation engine. Use the schema dialect supported by the tool and your target application. Worked example: If a schema lists "email" in its required array but the instance object omits the email property, validation should report that required-property violation. Common practical uses include Validate API request or response examples; Check configuration files against a schema; Develop and debug JSON Schemas; Test structured data contracts before integration. Important limitations: Supported JSON Schema drafts, vocabularies and format assertions depend on the underlying validator. Schema validation cannot enforce business rules that are not represented in the schema. A schema-valid document can still contain factually or semantically incorrect data. Key questions this page should answer include: What does a JSON Schema validator do? It checks JSON instance data against the structural and validation constraints defined by a JSON Schema. Is valid JSON automatically valid against a JSON Schema? No. JSON syntax can be valid while the data violates schema requirements such as type, required, enum or range constraints. What does a required property error mean? It means an object is missing a property that the schema requires at that location. Why does the JSON Schema draft matter?
How to use this tool
What JSON Schema validation checks
A schema can define expected data types, required object properties, array rules, numeric and string constraints, enumerated values and relationships between parts of a JSON document. The validator compares an instance against the constraints expressed by the supplied schema.
How to use the validator
- Paste or enter the JSON instance.
- Provide the JSON Schema in the format supported by the tool.
- Run validation.
- Use the reported instance path, schema rule and message to locate mismatches.
Valid JSON is not the same as schema-valid JSON
{"age":"twenty"} can be perfectly valid JSON syntax. If the schema requires age to be an integer, however, that instance fails schema validation.
JSON Schema drafts and dialects
JSON Schema has evolved through multiple drafts. Supported keywords, vocabularies and format behavior depend on the validation engine. Use the schema dialect supported by the tool and your target application.
Examples
Required property example
If a schema lists "email" in its required array but the instance object omits the email property, validation should report that required-property violation.
Common use cases
- Validate API request or response examples
- Check configuration files against a schema
- Develop and debug JSON Schemas
- Test structured data contracts before integration
Frequently asked questions
What does a JSON Schema validator do?
It checks JSON instance data against the structural and validation constraints defined by a JSON Schema.
Is valid JSON automatically valid against a JSON Schema?
No. JSON syntax can be valid while the data violates schema requirements such as type, required, enum or range constraints.
What does a required property error mean?
It means an object is missing a property that the schema requires at that location.
Why does the JSON Schema draft matter?
Different drafts and dialects support different keywords and semantics, so the validation engine needs to understand the schema version you are using.
Does JSON Schema validation prove my data is correct?
No. It shows whether the instance satisfies the constraints defined in the schema; it cannot verify rules or facts the schema does not express.