Which JSON Schema features are supported?

The common draft-07 subset: type, required, properties, items, enum, minimum/maximum, minLength/maxLength, pattern, `$ref` (local pointers only, e.g. `#/$defs/address`) and `allOf`. `anyOf`, `oneOf` and conditional (`if`/`then`/`else`) keywords aren't evaluated.

Does it resolve $ref against shared definitions?

Yes — a `$ref` like `#/$defs/address` or `#/definitions/address` is resolved and validated against, including refs used inside `allOf` to extend a shared definition. Only local refs within the same schema document are supported; a `$ref` pointing to an external URL can't be fetched and is reported as unresolvable rather than silently skipped.

Why validate model output if I asked for a schema?

Structured-output modes reduce but don't eliminate malformed responses, especially with older models or long outputs. Validating before use prevents downstream crashes.

No — validation runs in your browser.

JSON Schema Validator

Validate JSON data against a JSON Schema.

Processed locally in your browser. Nothing you paste is sent anywhere.

Data is valid against the schema.

Supports a common subset of JSON Schema draft-07 (type, required, properties, items, enum, min/max, pattern, $ref and allOf) — $ref only resolves local pointers within the same schema (e.g. #/$defs/...), and some advanced keywords (anyOf, oneOf, conditional if/then/else) aren't evaluated.

Lists every violation with the exact path to the offending value, not just pass/fail.
Fast feedback loop while you tune a structured-output prompt.
Runs in your browser — schema and data aren't uploaded.

Why this is private

Processed locally in your browser. Nothing you paste is sent anywhere.
Open your browser's DevTools → Network tab while using this tool — you won't see a request carrying your input, because it never leaves your device.
Nothing you enter is uploaded to a server or shared with us — the processing happens entirely on your device.

Overview

Validates a JSON value against a JSON Schema — useful for checking that a model's structured output actually conforms to the schema you asked for.

How to use it

1Paste your JSON Schema.
2Paste the JSON data to check.
3Validation errors, if any, are listed with their exact path.

Tips

Supports the common subset of draft-07 (type, required, properties, items, enum, min/max, pattern, $ref and allOf) — $ref only resolves local pointers within the same schema (e.g. #/$defs/... or #/definitions/...), and anyOf/oneOf/conditional keywords aren't evaluated.

Frequently asked questions

What people use it for

Verify an LLM's structured outputConfirm a model response matches the schema before your code relies on it.

Test a schema against sample dataCheck a schema you're writing accepts the valid cases and rejects the bad ones.

Debug a failing API requestFind which field in a payload breaks the endpoint's schema.

Document expected shapePaste a schema and a conforming example together for a teammate.

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Ready to use JSON Schema Validator?

JSON Schema Validator

JSON Schema Validator

Why this is private

Overview

How to use it

Tips

Frequently asked questions

Which JSON Schema features are supported?

Does it resolve $ref against shared definitions?

Why validate model output if I asked for a schema?

Is my data uploaded?

What people use it for

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