JSON Schema Validator

The tool supports JSON Schema Draft 2020-12 and Draft-07. The version comes from the schema's $schema keyword; without one, the version chosen under Draft is used (Draft 2020-12 by default). Other versions, such as Draft-04 or Draft 2019-09, are rejected rather than checked with the wrong rules.

$schema must be the official URI of the draft: https://json-schema.org/draft/2020-12/schema or http://json-schema.org/draft-07/schema#. As compatibility aliases, the same URIs with http and https swapped are also accepted: http://json-schema.org/draft/2020-12/schema and https://json-schema.org/draft-07/schema#. The value must match exactly; any other spelling, such as a missing or extra # or a trailing slash, is reported as an unsupported version.

Before your data is checked, the schema itself is checked against the official metaschema for its version, which is built into the page. An invalid schema, an invalid pattern or a $ref that cannot be resolved is reported as a schema error. A schema error means there is no verdict about the data: the schema has to be fixed first.

Errors are listed in a fixed order: for each part of the schema, keywords are checked in the same sequence every time, and array items and object properties are visited in the order they appear in the data. anyOf, oneOf and not report one error of their own instead of every error inside their subschemas. At most 100 errors are listed; the total is always shown.

Error messages only contain values from the schema, such as a maximum or a required property name. Values from your data are never repeated in messages; the path tells you where the problem is.

Numbers are compared by their exact decimal value, without floating-point rounding. 9007199254740993 does not satisfy a maximum of 9007199254740992, 1.0000001 is not a multiple of 1, and 0.30000000000000001 is not equal to 0.3, even though JavaScript reads those pairs as the same number. Many validators get these wrong because they convert numbers to floating point first.

1, 1.0 and 1e0 are the same number, and -0 equals 0. A number with no fractional part, such as 1.0, counts as an integer.

$ref is resolved only inside the schema you paste: JSON Pointers such as #/$defs/address, $id, $anchor and $dynamicAnchor. A reference to another URL, a file or any other location is never fetched; it is reported as a schema error. To use another schema, copy it under $defs (definitions in Draft-07) and refer to it locally. References to the official Draft 2020-12 and Draft-07 metaschemas work, because they are built in.

Recursive and mutually recursive schemas are supported. Validation stops with a message when references are followed more than 256 levels deep or after 1,000,000 steps.

The format keyword (email, uri, date-time and others) is treated as an annotation, as the 2020-12 specification does by default: it is not checked. When the schema uses format, the page says how many format keywords it found, so you know which values were not checked. Use pattern if a value must be enforced.

Both boxes must contain strict JSON (RFC 8259): comments, trailing commas and single quotes are rejected. An object that repeats a key is rejected, including keys that are only equal after escapes are resolved, such as "a" and "\u0061".

Each box is limited to 1,000,000 characters and to 128 levels of nested arrays and objects. Patterns are JavaScript regular expressions with the u flag.

Validation runs in a background worker and is stopped after 5 seconds, so a pattern that takes too long to match cannot freeze the page. If your browser cannot start a worker, the tool shows an error instead of validating on the page itself. Support has only been checked in Chromium-based browsers; Firefox and Safari are not verified.