keyword	$schema
signature	URI
value	This keyword must be set to an absolute URI as defined by [RFC 3986](https://www.rfc-editor.org/info/rfc3986)
summary	This keyword is both used as a JSON Schema dialect identifier and as a reference to a JSON Schema which describes the set of valid schemas written for this particular dialect.
kind	identifier
instance	any
specification	https://json-schema.org/draft-07/draft-handrews-json-schema-01#rfc.section.7
metaschema	http://json-schema.org/draft-07/schema#
default	description Implementation dependent
index	-999
introduced_in	draft3
related	vocabulary keyword core $id vocabulary keyword validation definitions

The [$schema]({{< ref "draft7/core/schema" >}}) keyword serves to explicitly associate a schema resource with the JSON Schema dialect that defines it, where the dialect is the identifier of a meta-schema that defines the keywords in use and imposes syntactic constraints on its schema instances. If the [$schema]({{< ref "draft7/core/schema" >}}) keyword is not declared, the schema inherits its context-specific or implementation-specific default dialect.

{{}} It is common to avoid the [$schema]({{< ref "draft7/core/schema" >}}) keyword when working with OpenAPI. This is possible because the OpenAPI specification clearly documents what the default JSON Schema dialect is for every version. For example, OpenAPI v3.1.1 defines the default dialect as https://spec.openapis.org/oas/3.1/dialect/base. {{}}

Strictly-compliant JSON Schema implementations will refuse to process a schema whose dialect cannot be unambiguously determined.

{{}} To avoid undefined behavior, it is generally recommended to always explicitly set the dialect of a schema using the [$schema]({{< ref "draft7/core/schema" >}}) keyword. This ensures that less strict implementations unambiguously know how to process the schema and don't attempt to guess.{{}}

Note that the [$schema]({{< ref "draft7/core/schema" >}}) keyword can occur multiple times in the same schema, and not only at the top-level. This is often the case when performing JSON Schema Bundling to inline externally referenced schemas that might be based on different dialects of JSON Schema.

{{}}JSON Schema prohibits referencing meta-schemas using relative URIs. The fundamental reason for this is that resolving the meta-schema is necessary for correctly determining the base URI of the schema, from which a relative meta-schema reference would be resolved, introducing a circular problem.

A common occurrence of this issue is setting the [$schema]({{< ref "draft7/core/schema" >}}) keyword to a relative path, which is again invalid according to the specification.{{}}

{{}}JSON Schema prohibits the use of the this keyword on arbitrary subschemas that do not represent schema resources. It can only be present at the root of the schema (an implicit schema resource) or as a sibling of the [$id]({{< ref "draft7/core/id" >}}) keyword (an explicit schema resource).{{}}

A schema is considered syntactic valid if it successfully validates against its dialect meta-schema. You can validate a schema against its meta-schema using the jsonschema metaschema command. For example:

$ jsonschema metaschema my-schema.json

To debug the role of the [$schema]({{< ref "draft7/core/schema" >}}) keyword on a schema (particularly schemas with embedded resources), try the jsonschema inspect command. This command prints detailed information about each schema resource, subschema, location, and reference present in the schema. For example:

$ jsonschema inspect schema.json
(RESOURCE) URI: https://example.com/schema
    Type              : Static
    Root              : https://example.com/schema
    Pointer           :
    Base              : https://example.com/schema
    Relative Pointer  :
    Dialect           : http://json-schema.org/draft-07/schema#
    Base Dialect      : http://json-schema.org/draft-07/schema#
    Parent            : <NONE>
    Instance Location :

...

(SUBSCHEMA) URI: https://example.com/schema#/properties/foo
    Type              : Static
    Root              : https://example.com/schema
    Pointer           : /properties/foo
    Base              : https://example.com/schema
    Relative Pointer  : /properties/foo
    Dialect           : http://json-schema.org/draft-07/schema#
    Base Dialect      : http://json-schema.org/draft-07/schema#
    Parent            :
    Instance Location : /foo

...

(REFERENCE) ORIGIN: /$schema
    Type              : Static
    Destination       : http://json-schema.org/draft-07/schema
    - (w/o fragment)  : http://json-schema.org/draft-07/schema
    - (fragment)      : <NONE>

Examples

{{<schema A schema described by the JSON Schema Draft 7 official dialect>}} { "$schema": "http://json-schema.org/draft-07/schema#", "type": "string" } {{}}

{{<schema A valid schema without an explicitly declared dialect, prone to undefined behavior>}} { "items": [ { "type": "number" } ] } {{}}

{{<schema A valid schema that mixes the Draft 7 and 2020-12 official dialects>}} { "$schema": "http://json-schema.org/draft-07/schema#", "properties": { "price": { "type": "number" }, "discount": { "$ref": "#/definitions/discount" } }, "definitions": { "discount": { "$schema": "https://json-schema.org/draft/2020-12/schema", "type": "number" } } } {{}}