id.markdown

keyword	id
signature	URI Reference
value	This keyword must be set to an absolute URI or a relative reference as defined by [RFC 3986](https://www.rfc-editor.org/info/rfc3986)
summary	This keyword declares an identifier for the schema resource.
kind	identifier
instance	any
specification	https://json-schema.org/draft-04/draft-zyp-json-schema-04#rfc.section.7.2
metaschema	http://json-schema.org/draft-04/schema#
tests	draft4/optional/id.json
index	-999
introduced_in	draft3
affects	vocabulary keyword core $ref
related	vocabulary keyword core $schema

The [id]({{< ref "draft4/core/id" >}}) keyword explicitly turns a schema into a schema resource (a schema that is associated with a URI). Relative URIs are resolved against the current base URI, which is either the closest parent [id]({{< ref "draft4/core/id" >}}) keyword (applicable in the case of compound schemas), or the base URI as determined by the context on which the schema is declared (i.e. serving a schema over HTTP may implicitly award it such URL as the base).

{{}}

This keyword directly applies (without modifications or extensions) the concept of URIs to schemas. If you are having a hard time following the concepts discussed in this page, it is probably because you don't have a strong grasp of URIs yet (a notably hard but universal pre-requisite!).

To learn more about URIs, we strongly suggest studying the IETF RFC 3986 URI standard. To avoid confusion, note that there is also a WHATWG URL Standard that targets URLs in the context of web browsers. However, JSON Schema only implements and expects the IETF original standard.

{{}}

{{}}

In JSON Schema, schema identifiers are merely identifiers and no behaviour is imposed on them. In particular, JSON Schema does not guarantee that a schema with an HTTP URL identifier is actually resolvable at such URL. To avoid surprises, JSON Schema implementations must be careful with automatically sending remote network requests when encountering supposely resolvable schema identifiers.

{{}}

{{}}

It is strongly recommended for every schema file to explicitly declare an absolute URI using this keyword. By doing so, you completely avoid various complex URI resolution edge cases, mainly when the base URI is implicit and context-dependent.

If you are serving schemas over the network (i.e. over HTTP), it is common to set this keyword to the target URL. However, if your schemas are not accessible over the network, prefer using a URN (with a valid namespace registered by IANA) or a non-locatable URI scheme such as a Tag URI.

{{}}

To debug the role of the [id]({{< ref "draft4/core/id" >}}) 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-04/schema#
    Base Dialect      : http://json-schema.org/draft-04/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-04/schema#
    Base Dialect      : http://json-schema.org/draft-04/schema#
    Parent            :
    Instance Location : /foo

...

(REFERENCE) ORIGIN: /$schema
    Type              : Static
    Destination       : http://json-schema.org/draft-04/schema
    - (w/o fragment)  : http://json-schema.org/draft-04/schema
    - (fragment)      : <NONE>

Examples

{{<schema A schema that declares a potentially resolvable HTTP absolute URL identifier>}} { "$schema": "http://json-schema.org/draft-04/schema#", "id": "https://example.com/schemas/even-number.json", "type": "number", "multipleOf": 2 } {{}}

{{<schema A schema that declares a non-resolvable Tag URI identifier>}} { "$schema": "http://json-schema.org/draft-04/schema#", "id": "tag:example.com,2025:even-number", "type": "number", "multipleOf": 2 } {{}}

{{<schema A schema that declares a non-resolvable URN example identifier>}} { "$schema": "http://json-schema.org/draft-04/schema#", "id": "urn:example:even-number", "type": "number", "multipleOf": 2 } {{}}

{{<schema A schema that uses fragment identifiers to create reusable anchors>}} { "$schema": "http://json-schema.org/draft-04/schema#", "id": "https://example.com/schemas/user.json", "type": "object", "properties": { "name": { "$ref": "#nonEmptyString" }, "email": { "$ref": "#nonEmptyString" } }, "definitions": { "nonEmptyString": { "id": "#nonEmptyString", "type": "string", "minLength": 1 } } } {{}}

{{<schema A compound schema that declares relative and absolute nested URIs>}} { "$schema": "http://json-schema.org/draft-04/schema#", "id": "https://example.com/schemas/root.json", "properties": { "foo": { "id": "foo.json" }, "bar": { "id": "/schemas/bar.json" }, "baz": { "id": "https://absolute.example/baz.json", "items": { "id": "deep" } } } } {{}}