curl --request POST \
  --url https://api.hubapi.com/events/custom/2026-03/event-definitions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "includeDefaultProperties": true,
  "label": "<string>",
  "propertyDefinitions": [
    {
      "label": "<string>",
      "type": "<string>",
      "description": "<string>",
      "name": "<string>",
      "options": [
        {
          "displayOrder": 123,
          "hidden": true,
          "label": "<string>",
          "value": "<string>",
          "description": "<string>"
        }
      ]
    }
  ],
  "customMatchingId": {
    "primaryObjectRule": {
      "eventPropertyName": "<string>",
      "targetObjectPropertyName": "<string>"
    }
  },
  "description": "<string>",
  "name": "<string>",
  "primaryObject": "<string>"
}
'

{
  "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,
      "modificationMetadata": {
        "archivable": true,
        "readOnlyDefinition": true,
        "readOnlyValue": true,
        "readOnlyOptions": true
      },
      "referencedObjectType": "<string>",
      "sensitiveDataCategories": [
        "<string>"
      ],
      "showCurrencySymbol": true,
      "updatedAt": "2023-11-07T05:31:56Z",
      "updatedUserId": "<string>"
    }
  ],
  "comboEventRules": {
    "composingRules": [
      {
        "count": 123,
        "eventTypeId": "<string>",
        "propertyFilters": [
          {
            "filterType": "PROPERTY",
            "operation": {
              "includeObjectsWithNoValueSet": true,
              "operationType": "<string>",
              "operator": "HAS_EVER_BEEN_EQUAL_TO",
              "operatorName": "<string>",
              "propertyType": "bool",
              "value": true,
              "defaultValue": "<string>",
              "renderSpec": "<string>"
            },
            "property": "<string>",
            "context": {
              "objectTypeId": "<string>"
            },
            "filterInsightsId": 123,
            "frameworkFilterId": 123
          }
        ],
        "lookbackWindowDays": 123
      }
    ],
    "operationType": "AND",
    "ruleBranches": "<array>"
  },
  "createdAt": "2023-11-07T05:31:56Z",
  "createdUserId": 123,
  "customMatchingId": {
    "primaryObjectRule": {
      "eventPropertyName": "<string>",
      "targetObjectPropertyName": "<string>"
    }
  },
  "description": "<string>",
  "primaryObject": "<string>",
  "primaryObjectId": "<string>",
  "trackingType": "APP_EVENT",
  "updatedAt": "2023-11-07T05:31:56Z",
  "updatedUserId": 123
}