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PUT
Update a contact
Update a contact by email or userId. You must provide one of these parameters. If you want to update a contact’s email address, the contact will first need a userId value. You can then make a request containing the userId field along with an updated email address. This endpoint will create a contact if a matching contact does not already exist in your audience.
Provide either email or userId to identify the contact you want to update. If both are provided, the system will look for a contact with either a matching email or userId value. If a contact is found for one of the values (e.g. email), the other value (e.g. userId) will be updated. If a contact is not found, a new contact will be created using both email and userId values.

Authorizations

Authorization
string
header
required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Body

application/json

You can add custom contact properties as keys in this request (of type string, number, boolean or date. See available date formats). Make sure to create the properties in Loops before using them in API calls.

email
string
required

The contact's email address. Required if userId is not provided.

firstName
string

The contact's first name.

lastName
string

The contact's last name.

source
string

A custom source value to replace the default “API”.

subscribed
boolean

Whether the contact will receive campaign and workflow emails. We recommend leaving this field out of your update requests unless you specifically want to unsubscribe (false) or re-subscribe (true) a contact. All new contacts are subscribed by default.

userGroup
string

You can use groups to segment users when sending emails. Currently, a contact can only be in one user group. Read more

userId
string

The contact's unique user ID. Required if email is not provided.

mailingLists
object

Manage mailing list subscriptions.

Include key-value pairs of mailing list IDs and a boolean denoting if the contact should be added (true) or removed (false) from the list.

Example:
{key}

Response

Successful update.

success
boolean
required
Example:

true

id
string
required
Last modified on July 17, 2026