curl --request GET \
  --url https://api.hubapi.com/events/custom/2026-03/event-definitions \
  --header 'Authorization: Bearer <token>'

{
  "results": [
    {
      "archived": true,
      "associations": [
        {
          "allowsCustomLabels": true,
          "cardinality": "ONE_TO_MANY",
          "category": "HUBSPOT_DEFINED",
          "fromObjectTypeId": "<string>",
          "hasAllAssociatedObjects": true,
          "hasCascadingDeletes": true,
          "hasUserEnforcedMaxFromObjectIds": true,
          "hasUserEnforcedMaxToObjectIds": true,
          "hidden": true,
          "id": 123,
          "inverseAllowsCustomLabels": true,
          "inverseCardinality": "ONE_TO_MANY",
          "inverseHasAllAssociatedObjects": true,
          "inverseId": 123,
          "inverseName": "<string>",
          "isDefault": true,
          "isInversePrimary": true,
          "isPrimary": true,
          "maxFromObjectIds": 123,
          "maxToObjectIds": 123,
          "name": "<string>",
          "portalUniqueIdentifier": "<string>",
          "readOnly": true,
          "toObjectTypeId": "<string>",
          "fromObjectType": "ABANDONED_CART",
          "hiddenReason": "DEFAULT",
          "inverseLabel": "<string>",
          "label": "<string>",
          "toObjectType": "ABANDONED_CART"
        }
      ],
      "fullyQualifiedName": "<string>",
      "id": "<string>",
      "labels": {
        "singular": "<string>",
        "plural": "<string>"
      },
      "name": "<string>",
      "objectTypeId": "<string>",
      "properties": [
        {
          "description": "<string>",
          "fieldType": "<string>",
          "groupName": "<string>",
          "label": "<string>",
          "name": "<string>",
          "options": [
            {
              "hidden": true,
              "label": "<string>",
              "value": "<string>",
              "description": "<string>",
              "displayOrder": 123
            }
          ],
          "type": "<string>",
          "archived": true,
          "archivedAt": "2023-11-07T05:31:56Z",
          "calculated": true,
          "calculationFormula": "<string>",
          "createdAt": "2023-11-07T05:31:56Z",
          "createdUserId": "<string>",
          "dataSensitivity": "highly_sensitive",
          "dateDisplayHint": "absolute",
          "displayOrder": 123,
          "externalOptions": true,
          "formField": true,
          "hasUniqueValue": true,
          "hidden": false,
          "hubspotDefined": true,
          "referencedObjectType": "<string>",
          "sensitiveDataCategories": [
            "<string>"
          ],
          "showCurrencySymbol": true,
          "updatedAt": "2023-11-07T05:31:56Z",
          "updatedUserId": "<string>"
        }
      ],
      "createdAt": "2023-11-07T05:31:56Z",
      "createdUserId": 123,
      "description": "<string>",
      "primaryObject": "<string>",
      "primaryObjectId": "<string>",
      "trackingType": "APP_EVENT",
      "updatedAt": "2023-11-07T05:31:56Z",
      "updatedUserId": 123
    }
  ],
  "total": 123,
  "paging": {}
}