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.

Schema: 0 chars · 0 BInstance: 0 chars · 0 B

Strict mode

Share this tool:

JSON Schema

JSON instance

Result

Draft-07 and 2020-12 only. Schema ≠ JSON syntax — use JSON Validator for syntax. External $ref are never fetched.

Paste a schema and instance to validate

Validation runs in your browser — nothing is uploaded.

Loading…

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 <strong>syntax</strong> only. This tool checks whether data conforms to a <strong>JSON Schema</strong> (Draft-07 or 2020-12).