Online JSON Schema validation tool: validate JSON data against JSON Schema definitions. Supports format validation, type checking, required fields.
TL;DR: Free online JSON Schema validator. Validate JSON data against schema definitions with format checks, type checking, and required field verification. Runs locally in your browser, no registration.
For local tools, open DevTools → Network and search your input — it should not appear in requests.
Next steps
Usage Guide
Validate JSON with JSON Schema locally via ajv and formats.
1. Validate
Paste instance and schema; read paths/keywords; iterate.
2. Authoring order
Structure first, then formats/bounds; be deliberate with additionalProperties.
3. Toolchain
Draft → edit → validate pos/neg cases; same file in CI.
4. Formats
Enforced here via ajv-formats; nullable ≠ missing.
5. Errors
Ownership decides whether to fix data or widen schema.
6. Non-goals
Not auth, idempotency, or business rules.
FAQ
Yes. Validation runs on ajv (with the format extension) inside your browser, and neither your sample data nor your schema definition is sent anywhere along the way.
Every violation is listed with its instancePath (where it failed) and keyword. required means a field is missing, type means the value has the wrong type, and enum means the value falls outside the allowed set — three keywords, three different fixes.
Yes. Formats only get enforced with ajv's format plugin, and this page already includes ajv-formats. If you reuse the same schema elsewhere, make sure that validator enables format support too — otherwise those keywords do nothing.
Structure first, refinements second: start with type, properties, and required, then add format/pattern and numeric ranges; for arrays settle items (prefixItems in 2020-12) before minItems. Think twice before setting additionalProperties:false on a public API — it rejects every extension field unless rejection is exactly what you want.
Model them separately: type:[string,null] means the field exists and may be null, while required only checks whether the key is present. Conflating the two is a common source of false errors — an explicit null is not a missing key.
Draft with the generator, tighten in an editor, then regression-test here with both positive and negative samples — keep cases like missing fields, wrong types, and out-of-enum values. Run the same schema file in CI so it's not only green in the browser.
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