Contacts

A contact represents a person in your audience. Contacts have channels (email, phone), custom fields, tags, list memberships, subscription state, and an activity history.

Channels

Each contact can have multiple communication channels:

• Email — for email campaigns and transactional messages
• Phone — for SMS messages

Custom fields

Custom fields hold anything else you know about a contact, such as a plan or a signup source. Set them inside the contact's data object when you create or update the contact, through the REST API or attributes.data in the nitro_manage_audience MCP tool:

{
  "email": "alice@example.com",
  "data": { "plan": "pro", "signup_source": "webinar" }
}

A key sent at the top level instead of inside data is ignored. New keys are registered automatically, so you can use them in segment conditions and in templates, where you reference one as {{ data.plan }} (see personalization).

Integration fields are written by their sync under the integration's name, such as data.shopify, and can't be set through the API.

Tags

Tags are free-form labels you can attach to contacts (for example vip, newsletter, free-trial). Tags are a special reserved key on each contact's data object — stored as an array of strings — and are used for segmentation and targeting alongside lists and custom fields.

Unlike lists, tags are lightweight: a contact can have any number of tags. You can set the tags on an individual contact via the REST API, or add, remove, and replace tags across many contacts at once via the nitro_manage_audience MCP tool.

Subscription status

Contacts can be subscribed, unsubscribed, or bounced per channel. Unsubscribed contacts are automatically excluded from campaigns.

Activity timeline

Each contact has an activity timeline showing sends, opens, clicks, unsubscribes, bounces, complaints, custom events, and list changes in one place. Use it to understand how a contact reached their current state before you target them again.

Saved views

The contacts table supports saved views. A saved view keeps the current search, filters, visible columns, and sort order so you can return to an operational slice of your audience quickly.

Saved views are for working in the contacts table. Use segments when the same rules should become a reusable audience for campaigns, flows, or agents.