JSON Schema Validator
Free online JSON Schema validator. Check any JSON document against a draft-07 or 2020-12 schema and get instant errors with path, keyword and message — powered by Ajv, entirely in your browser.
What is a JSON Schema validator?
It checks whether a JSON document conforms to a schema — a formal description of the allowed types, fields, ranges and patterns. The validator reports every violation with the location in your data, the violated keyword and a readable message, so you can fix the document or the schema immediately.
Which JSON Schema versions are supported?
Draft-07 and Draft 2020-12, selectable from the Draft dropdown at the top. The matching Ajv validator is used for the version you pick, so keywords unique to each draft behave exactly as their specification defines.
How do I validate my data?
Paste or load your JSON instance in the left pane and your schema in the right pane. Validation runs automatically about 300 ms after you stop typing, so there is no button to press. The Example buttons fill both panes with a working sample you can then break on purpose to see errors.
What information does each error show?
Three things: the path to the offending value in your data (like /user/emails/2), the schema keyword that failed (required, type, minimum, enum and so on) and the original Ajv message in English, which you can copy straight into an issue tracker.
Can I load files instead of pasting?
Yes. Each pane has a Load file button that reads a .json or .txt file from your device directly into that pane. Large schemas and API payloads work fine because everything is processed locally.
Is my data uploaded anywhere?
No. Parsing, schema compilation and validation all run inside your browser with Ajv bundled into the page. Nothing is sent to any server; your last inputs are only kept in this browser's local storage.
When do I need JSON Schema validation?
Checking API request and response payloads, validating configuration files before deployment, testing code that generates JSON, or QA-ing data pipelines. It is the fastest way to see exactly where a document breaks the contract described by the schema.
What is the difference between draft-07 and 2020-12?
Draft 2020-12 replaced draft-07 in 2020. It added prefixItems for tuples, redefined items to apply to every position, unified $ref handling and introduced $dynamicRef. If your schema declares a draft via $schema, that declaration is ignored here — choose the version with the dropdown instead.
How to Use JSON Schema Validator
This tool checks whether a JSON document conforms to a JSON Schema. It bundles both Ajv draft-07 and Ajv 2020-12 validators, so you can pick the draft version your schema targets. The left pane holds your JSON instance, the right pane your schema, and validation runs automatically with a short debounce as you type. Results appear as a green valid badge or a detailed error list with the path into your data, the failed keyword and the original Ajv message. Everything runs locally in your browser — nothing is uploaded.
- Paste your JSON data into the left textarea, or press its Example or Load file button to fill it.
- Paste your JSON Schema into the right textarea, or use its Example / Load file buttons.
- Pick the schema draft from the dropdown: Draft-07 (the most widespread) or Draft 2020-12.
- Wait a moment — validation runs automatically about 300 ms after you stop typing and re-runs on every edit.
- Read the result: a green Valid banner means the instance conforms; otherwise each error shows the path (like /tags/0), the keyword (required, type, minimum…) and the original Ajv message.
- Clear wipes both panes and the saved state; your inputs are kept in this browser's local storage between visits.
The required keyword reports the error on the parent object, so the path shown is the object that is missing a property, not the property itself. A schema's own $schema and $id keys are ignored — the version is controlled only by the Draft dropdown. Switch drafts to compare how a legacy draft-07 schema behaves under 2020-12.
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