JSON Schema Validator
Validate JSON data against JSON Schema
Paste the JSON and schema first to see validation results; strict mode and stop-first-error are available in Advanced mode.
Only a subset of schema rules is checked. Unimplemented keywords such as $ref, composition, format, and additionalProperties are ignored. This result does not establish full JSON Schema validity; Strict mode is a tool-specific property allowlist.
The full guide also includes pitfalls, worked examples, snippets, FAQs, and related tools for checking results or troubleshooting.
About this tool
Run a limited set of JSON Schema-style checks locally and inspect field-level errors. Supported rules include basic types, scalar enums, numeric bounds, string constraints, and typed object or array children. Unsupported keywords can be ignored; a passing result is not full JSON Schema validation. Strict mode adds a local property allowlist. Inputs and options are saved in this browser.
Failure Clinic (Common Pitfalls)
Unsupported rules produce a passing subset result
Cause: Keywords such as $ref, oneOf, format, and additionalProperties are not evaluated. Object and array traversal also requires the corresponding explicit type; scalar enum comparison does not implement object/array equality.
Fix: Read the result as implemented checks only. Validate real contracts with a complete JSON Schema implementation for the required draft, including references and schema validation.
Production Snippets
A numeric bound that this checker implements
text
Data:
{"count":2}
Schema:
{"type":"object","properties":{"count":{"type":"integer","minimum":3}}}
Reported error:
$.count: should be >= 3Frequently Asked Questions
Which rules are implemented?
The local checker covers a single type, scalar enum values, minimum/maximum, string minLength/maxLength/pattern, and typed object properties/required or typed array items. String lengths use JavaScript UTF-16 code units. It does not implement a complete JSON Schema draft.
What does Supported checks passed mean?
No error was found by the implemented checks. $ref, allOf/anyOf/oneOf, const, format, additionalProperties, tuple schemas, boolean schemas, and many other rules are unsupported or ignored. Use a full validator for an API contract or release gate.
What does Strict mode do?
For a schema with type: object and properties, this local option rejects data keys not listed in properties, regardless of additionalProperties. Without the option, extra keys are not checked. It is not JSON Schema strict-mode compatibility.
Are data or schemas stored?
Validation does not upload either input. Both inputs and options are saved in this browser’s local storage; clear each input to remove its saved content.
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