# Get Custom Entities Metadata

The metadata is a JSON Schema document that lists the Custom Entities defined in the PIM
for the current tenant, together with their relationships. Use the returned denominators
to query individual Custom Entity schemas via GET /CustomEntities('{denominator}')/$metadata.
            
## Authentication
            
Requires a valid API key in the X-API-KEY header.
            
## Response
            
200 OK — Returns the JSON Schema as a ServiceDocumentRepresentation.
            
## Error Responses
            
- 401 Unauthorized — Missing or invalid API key.
- 404 Not Found — Tenant not found.
- 500 Internal Server Error — Unexpected technical error.
            
## Example
            
Request:
http
GET /CustomEntities/$metadata HTTP/1.1
X-API-KEY: your-api-key-here

            
Response:
http
HTTP/1.1 200 OK
Content-Type: application/json

Endpoint: GET /CustomEntities/$metadata
Version: 2.0.0

## Header parameters:

  - `X-API-KEY` (string)
    Tenant's API key (required)

## Response 200 fields (application/json):

  - `readLink` (object)

  - `readLink.uri` (string,null)

  - `value` (any,null)

## Response 400 fields (application/json):

  - `validationFailures` (object,null)
    Example: {"Layout":[{"PropertyName":"Layout","ErrorMessage":"The layout must contain exactly the attributes of the stored layout. Missing: tags. Unknown: extra_field.","AttemptedValue":null}]}

## Response 401 fields (application/json):

  - `type` (string,null)

  - `title` (string,null)

  - `status` (integer,null)

  - `detail` (string,null)

  - `instance` (string,null)

## Response 500 fields (application/json):

  - `error` (string,null)

  - `details` (any,null)