JSON Schema Validator Online — Draft-07 & 2020-12

Validate JSON data against a JSON Schema in your browser. Schema vs instance — not a JSON syntax checker. External $ref are never fetched.

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JSON Schema Validator documentation
Validate JSON instances against Draft-07 or 2020-12 schemas.

Developer notes

• Uses ajv (+ ajv-formats) via dynamic import — Draft-07 and 2020-12 only. • Missing $schema defaults to 2020-12; Draft-04/06/2019-09 are rejected (not coerced). • Optional Strict mode enables Ajv strict: true (unknown keywords fail at compile). • Dual editors: schema + instance; live debounce ~300 ms. • External $ref → hard error (never fetched). • This is schema validation — not JSON syntax-only (see JSON Validator). • Max 512 KiB per field.

Options

Strict mode
Off by default (Ajv strict: false). On enables Ajv strict mode so unknown keywords and other non-strict schemas fail at compile time — useful for CI / schema review.

Use cases

• Check API payloads against a JSON Schema before shipping. • Debug instancePath / keyword errors locally. • Pair with OpenAPI converters when schemas live in components.schemas.

Examples

Valid instance

Schema

{ "$schema": "https://json-schema.org/draft/2020-12/schema", "type": "object", "required": ["id", "name"], "properties": { "id": { "type": "integer" }, "name": { "type": "string" } } }

Instance

{ "id": 1, "name": "Rex" }

Invalid instance

Schema

{ "type": "object", "required": ["id"], "properties": { "id": { "type": "integer" } } }

Instance

{ "name": "missing id" }

JSON Schema Validator FAQ

Common questions

Is this the same as JSON Validator?

No. JSON Validator checks syntax only. This tool checks whether data conforms to a JSON Schema (Draft-07 or 2020-12).

Which drafts are supported?

Draft-07 and 2020-12. If $schema is missing, 2020-12 is used. Draft-04, Draft-06, and 2019-09 return a clear unsupported-draft error.

Are remote $ref resolved?

No. External and http(s) $ref are hard errors — nothing is fetched from the network.

Related tools?

Convert schemas with JSON Schema to OpenAPI / OpenAPI to JSON Schema, or check JSON syntax with JSON Validator.

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