curl --request POST \
  --url https://api.hubapi.com/events/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>"
        }
      ]
    }
  ],
  "description": "<string>",
  "name": "<string>",
  "primaryObject": "<string>"
}
'

import requests

url = "https://api.hubapi.com/events/2026-03/event-definitions"

payload = {
    "includeDefaultProperties": True,
    "label": "<string>",
    "propertyDefinitions": [
        {
            "label": "<string>",
            "type": "<string>",
            "description": "<string>",
            "name": "<string>",
            "options": [
                {
                    "displayOrder": 123,
                    "hidden": True,
                    "label": "<string>",
                    "value": "<string>",
                    "description": "<string>"
                }
            ]
        }
    ],
    "description": "<string>",
    "name": "<string>",
    "primaryObject": "<string>"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    includeDefaultProperties: true,
    label: '<string>',
    propertyDefinitions: [
      {
        label: '<string>',
        type: '<string>',
        description: '<string>',
        name: '<string>',
        options: [
          {
            displayOrder: 123,
            hidden: true,
            label: '<string>',
            value: '<string>',
            description: '<string>'
          }
        ]
      }
    ],
    description: '<string>',
    name: '<string>',
    primaryObject: '<string>'
  })
};

fetch('https://api.hubapi.com/events/2026-03/event-definitions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.hubapi.com/events/2026-03/event-definitions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'includeDefaultProperties' => true,
    'label' => '<string>',
    'propertyDefinitions' => [
        [
                'label' => '<string>',
                'type' => '<string>',
                'description' => '<string>',
                'name' => '<string>',
                'options' => [
                                [
                                                                'displayOrder' => 123,
                                                                'hidden' => true,
                                                                'label' => '<string>',
                                                                'value' => '<string>',
                                                                'description' => '<string>'
                                ]
                ]
        ]
    ],
    'description' => '<string>',
    'name' => '<string>',
    'primaryObject' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.hubapi.com/events/2026-03/event-definitions"

	payload := strings.NewReader("{\n  \"includeDefaultProperties\": true,\n  \"label\": \"<string>\",\n  \"propertyDefinitions\": [\n    {\n      \"label\": \"<string>\",\n      \"type\": \"<string>\",\n      \"description\": \"<string>\",\n      \"name\": \"<string>\",\n      \"options\": [\n        {\n          \"displayOrder\": 123,\n          \"hidden\": true,\n          \"label\": \"<string>\",\n          \"value\": \"<string>\",\n          \"description\": \"<string>\"\n        }\n      ]\n    }\n  ],\n  \"description\": \"<string>\",\n  \"name\": \"<string>\",\n  \"primaryObject\": \"<string>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.hubapi.com/events/2026-03/event-definitions")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"includeDefaultProperties\": true,\n  \"label\": \"<string>\",\n  \"propertyDefinitions\": [\n    {\n      \"label\": \"<string>\",\n      \"type\": \"<string>\",\n      \"description\": \"<string>\",\n      \"name\": \"<string>\",\n      \"options\": [\n        {\n          \"displayOrder\": 123,\n          \"hidden\": true,\n          \"label\": \"<string>\",\n          \"value\": \"<string>\",\n          \"description\": \"<string>\"\n        }\n      ]\n    }\n  ],\n  \"description\": \"<string>\",\n  \"name\": \"<string>\",\n  \"primaryObject\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.hubapi.com/events/2026-03/event-definitions")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"includeDefaultProperties\": true,\n  \"label\": \"<string>\",\n  \"propertyDefinitions\": [\n    {\n      \"label\": \"<string>\",\n      \"type\": \"<string>\",\n      \"description\": \"<string>\",\n      \"name\": \"<string>\",\n      \"options\": [\n        {\n          \"displayOrder\": 123,\n          \"hidden\": true,\n          \"label\": \"<string>\",\n          \"value\": \"<string>\",\n          \"description\": \"<string>\"\n        }\n      ]\n    }\n  ],\n  \"description\": \"<string>\",\n  \"name\": \"<string>\",\n  \"primaryObject\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "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>",
      "currencyPropertyName": "<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
      },
      "numberDisplayHint": "currency",
      "referencedObjectType": "<string>",
      "sensitiveDataCategories": [
        "<string>"
      ],
      "showCurrencySymbol": true,
      "textDisplayHint": "domain_name",
      "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>",
              "propertyAspect": {
                "aspect": "TIMERANGE_END",
                "qualifier": "<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>",
  "detailTemplate": "<string>",
  "headerTemplate": "<string>",
  "primaryObject": "<string>",
  "primaryObjectId": "<string>",
  "trackingType": "APP_EVENT",
  "updatedAt": "2023-11-07T05:31:56Z",
  "updatedUserId": 123
}

{
  "message": "Invalid input (details will vary based on the error)",
  "correlationId": "aeb5f871-7f07-4993-9211-075dc63e7cbf",
  "category": "VALIDATION_ERROR",
  "links": {
    "knowledge-base": "https://www.hubspot.com/products/service/knowledge-base"
  }
}