Dialects

Officially supported dialects (JSON Schema specification versions):

Draft 2020-12,
Draft 2019-09,
Draft 07,
Draft 06,
Draft 04.

It is automatically inferred (by the value of the $schema keyword) which dialect to use. If a schema does not contain the $schema keyword, the default dialect will be used, which is draft 2020-12 dialect. It's possible to change the default dialect by calling:

new ValidatorFactory().withDefaultDialect(new Dialects.Draft2019Dialect());

Meta-schemas

Each schema is recommended to contain the $schema keyword to properly infer which dialect to use. $schema keyword must refer to a meta-schema against which the current schema will be validated. Resolution of meta-schemas follows the same rules as for regular schemas.

There is a configuration option that disables all schema validations:

new ValidatorFactory().withDisabledSchemaValidation(true);

Note that this option will also turn off meta-schema resolution mechanics and will fall back to the matching predefined dialect or the default one.

Importance of dialects

Every schema needs to be understood in the context of a specific dialect. Dialects consist of a few vital parts:

Specification version - parsing schemas might behave differently depending on version value.
Evaluator Factory - class responsible for the creation of evaluators which in turn contain (mostly) validation logic.
Meta-schema URI (optional) - every schema in this dialect must be valid against this meta-schema.
Vocabularies (optional) - first appeared in the Draft 2019-09 specification, but it's not strictly limited to the newest versions only. You can define which vocabularies are supported, required and enabled by default.

	Draft 2020-12	Draft 2019-09	Draft 07	Draft 06	Draft 04
Spec version	SpecificationVersion.DRAFT2020_12	SpecificationVersion.DRAFT2019_09	SpecificationVersion.DRAFT7	SpecificationVersion.DRAFT6	SpecificationVersion.DRAFT4
Evaluator factory	Draft2020EvaluatorFactory	Draft2019EvaluatorFactory	Draft7EvaluatorFactory	Draft6EvaluatorFactory	Draft4EvaluatorFactory
Meta-schema	https://json-schema.org/draft/2020-12/schema	https://json-schema.org/draft/2019-09/schema	http://json-schema.org/draft-07/schema#	http://json-schema.org/draft-06/schema#	http://json-schema.org/draft-04/schema#
Supported vocabs	https://json-schema.org/draft/2020-12/vocab/core https://json-schema.org/draft/2020-12/vocab/applicator https://json-schema.org/draft/2020-12/vocab/unevaluated https://json-schema.org/draft/2020-12/vocab/validation https://json-schema.org/draft/2020-12/vocab/meta-data https://json-schema.org/draft/2020-12/vocab/format-annotation https://json-schema.org/draft/2020-12/vocab/format-assertion https://json-schema.org/draft/2020-12/vocab/content	https://json-schema.org/draft/2019-09/vocab/core https://json-schema.org/draft/2019-09/vocab/applicator https://json-schema.org/draft/2019-09/vocab/validation https://json-schema.org/draft/2019-09/vocab/meta-data https://json-schema.org/draft/2019-09/vocab/format https://json-schema.org/draft/2019-09/vocab/content	-	-	-
Required vocabs	https://json-schema.org/draft/2020-12/vocab/core	https://json-schema.org/draft/2019-09/vocab/core	-	-	-

Custom dialects

Please see a dedicated chapter Custom dialects.

04 August 2025