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JSON Schema Validator

Paste a JSON document and a schema, get a green check or per-path errors. Powered by Ajv. Runs entirely in your browser — your data never leaves the page.

JSON Validator

Validate
Valid
Data
Loading editor…
Schema
Loading editor…
Document conforms to the schema. No errors.

What is JSON Schema validation?

JSON Schema is a vocabulary for declaring the shape of a JSON document — required keys, value types, formats, ranges, enum members, nested structures, and so on. A schema validator runs the rules against a candidate document and reports which fields fail and why.

JSONZen uses Ajv 8 with the ajv-formats plugin, so format keywords like "email", "uri", and "date-time" behave the way you’d expect from a spec-faithful Ajv install.

When do you reach for it?

  • You wrote a schema to enforce an API contract and want to spot-check responses.
  • You’re onboarding to a tool whose config is JSON-Schema-driven and you want to understand its rules.
  • A request keeps failing with a vague 400 — paste the body + the schema and find the exact field that violates.

How to use it

  1. Paste your data into the left panel.
  2. Paste your JSON Schema into the right panel.
  3. Read the status badge — Valid, an error count, or a parse-error label if either input isn’t valid JSON.
  4. When errors are present, the bottom panel lists each one with its instancePath (which field) and the keyword that failed.

Frequently asked questions.

Which JSON Schema drafts do you support?
Ajv 8 underlies the validator. Drafts 7, 2019-09, and 2020-12 are supported. Draft 4/6 schemas usually work too with minor adjustments.
Do you support format keywords like "email" or "date-time"?
Yes. ajv-formats is enabled, so format: "email", "date", "date-time", "uri", "uuid", and the rest of the standard formats are checked.
Will my schema or data leave my browser?
No. Everything happens client-side. Nothing is uploaded, logged, or analytics-tracked.
Can I validate against $ref-ed remote schemas?
Local $refs work. Remote $refs (HTTP) are out of scope for this slice — paste the referenced schema inline for now.
How big a document can I validate?
Up to ~10 MB without lag. For larger inputs the editor stays responsive thanks to React’s deferred-value rendering, but the first validate pass can take a moment.

More JSON tools.

    JSON Schema Validator — Free, Client-Side, No Signup | JSONZen