# Custom Field Definitions

 - [GET /custom-field-definitions](https://docs.pers.ninja/swagger/custom-field-definitions/customfielddefinitionscontroller_listdefinitions.md): Get all custom field definitions for the tenant. Filter by entityType to get fields for a specific entity.
 - [POST /custom-field-definitions](https://docs.pers.ninja/swagger/custom-field-definitions/customfielddefinitionscontroller_create.md): Create a new custom field for the tenant. Key must be unique within tenant+entityType.
 - [GET /custom-field-definitions/{id}](https://docs.pers.ninja/swagger/custom-field-definitions/customfielddefinitionscontroller_getbyid.md): Get a single custom field definition by ID.
 - [PUT /custom-field-definitions/{id}](https://docs.pers.ninja/swagger/custom-field-definitions/customfielddefinitionscontroller_update.md): Update field properties. Key and entityType cannot be changed.
 - [DELETE /custom-field-definitions/{id}](https://docs.pers.ninja/swagger/custom-field-definitions/customfielddefinitionscontroller_delete.md): Delete a field. Fails if field is referenced in any redemption baseRequiredUserFields/specificRequiredUserFields or campaign.
 - [GET /custom-field-definitions/{id}/usages](https://docs.pers.ninja/swagger/custom-field-definitions/customfielddefinitionscontroller_getusages.md): Check if a field is referenced in any redemption or campaign. Useful before deletion.