JSON Schema Validator
Validate any JSON document against a JSON Schema (draft 2020-12 or draft-07). Each violation reports the JSON path, the expected constraint, and what was found. Useful for sanity-checking an API response against the schema, or for verifying that an LLM's structured output matches its declared schema.
How to use the JSON Schema Validator
Paste the schema on the left, the data on the right, click Validate. The Draft selector defaults to Auto, which reads the schema's $schema keyword to choose draft 2020-12 or draft-07; set it explicitly if your schema omits $schema. Errors list the JSON Pointer path of each violation (the standard /property/0/field notation that Ajv uses). String format values such as email, date-time, and uri are validated, not just annotated.
Validating JSON against a schema
Valid JSON syntax is no guarantee that the data is correct: a field might be missing, a number might be out of range, or a string might not match the required format. A JSON Schema captures those rules, and validating against it turns a vague “looks fine” into a precise list of what conforms and what does not.
This validates a document against a JSON Schema (draft 2020-12 or draft-07) and reports each violation with its JSON Pointer path, the constraint expected, and the value found — the same /items/0/email notation Ajv uses. It checks conformance to a schema; to instead check that text is syntactically strict JSON, the strict JSON validator is the right tool, and to create data that satisfies a schema, the schema to example generator works the other direction.
Common use cases
- Check an API response — confirm a payload matches its declared schema.
- Validate LLM output — verify a model’s structured response conforms.
- Pinpoint violations — get the exact JSON Pointer path of each error.
- Support two drafts — validate against draft 2020-12 or draft-07.
- Gate a pipeline — reject data that fails the schema before it moves on.