We recommend regularly updating contacts by Backend API (server-to-server). Request example:

{
  "firstName": "John",
  "lastName": "Smith",
  "channels": [
    {
      "type": "email",
      "value": "john.smith@example.com"
    },
    {
      "type": "sms",
      "value": "+1234567890"
    },
    {
      "type": "webPush",
      "value": "subscription-id-12345"
    }
  ],
  "address": [
    {
      "name": "city",
      "value": "New York"
    },
    {
      "name": "region",
      "value": "NY"
    },
    {
      "name": "country",
      "value": "US"
    },
    {
      "name": "postalCode",
      "value": "10001"
    },
    {
      "name": "addressLine",
      "value": "123 Main Street"
    }
  ],
  "fields": [
    {
      "name": "birthDate",
      "value": "1990-01-01"
    },
    {
      "name": "loyaltyLevel",
      "value": "Gold"
    }
  ],
  "externalCustomerId": "EM12790",
  "groups": [
    {
      "id": 1001,
      "name": "Newsletter Subscribers"
    }
  ],
  "languageCode": "en",
  "timeZone": "America/New_York"
}

Explanation of Fields:

firstName:
- Value: "John"
- The contact's first name.
lastName:
- Value: "Smith"
- The contact's last name.
channels:
- An array specifying the contact's communication channels. Each channel includes:
  - type: The channel type (e.g., "email", "sms", "webPush").
  - value: The identifier for the channel (e.g., email address, phone number).
address:
- Contains the contact's full address details:
  - city, region, country, postalCode, and addressLine.
fields:
- An array of custom fields containing additional information about the contact:
  - Example: "birthDate" and "loyaltyLevel".
externalCustomerId:
- Value: "EM12790"
- Your system's unique identifier for the contact.
groups:
- An array of static segments (groups) the contact belongs to.
- Example: "Newsletter Subscribers".
languageCode:
- Value: "en"
- The contact's preferred language.
timeZone:
- Value: "America/New_York"
- The contact's time zone.

📘
Note
We strongly recommend using your External ID as the main identifier to match the contact data in our system.