Custom Properties let you store additional contact information beyond default fields like email address, name, and phone number. Use them to save brand-specific data such as product preferences, preferred newsletter type, and more. This data helps you personalize campaigns and segment your audience.

You can add custom properties to contact profiles using the following methods:

Learn how each method works below.

To add a custom property to a signup form, go to the Forms tab and open or create a form. Then, drag and drop a Dropdown, Input, or Date field into the form. In the field settings, select Custom property under the Map to profile field option.

If you used a Dropdown item, you can add custom property values under Manage your choices.

The Subscriber Preference Center allows your contacts to update their preferences, including custom properties such as product interests, communication frequency, or preferred topics.

To add custom properties to the Preference Center, go to Store settings → Preference management → Add new field → select Custom property.

To add a custom property to a single contact, go to Audience → Contacts → Click the contact's name to open the contact profile page → Click Edit.

In the Edit profile details tab, switch to the Custom tab and click Add property. From there, you can select an existing custom property or create a new one.

When importing contacts from a CSV file, you can create and populate custom properties by mapping your file columns to custom properties.

During the Map properties step, click the dropdown next to the column you want to map → Scroll down and select Custom Property → Start typing the name of your custom property. If it doesn’t exist, you’ll see a Create New option appear.

You can use the Omnisend API to send custom property data from third-party apps, integrations, or your own custom events. You can create, update, and sync custom properties automatically using API.

To view custom properties, open a contact profile and find the Custom Properties section in the left-hand menu.

You can use custom properties to personalize messages and segment your audience.

When you export your contacts, each custom property generates a stand-alone row with different values assigned to your contacts.

I created a custom property, but it doesn't appear in my segment filters. Why?

Custom properties only appear in segment filters after at least one contact has been assigned that property. Go to Audience → Segments → Create Segment → Create from Scratch, then scroll all the way down to the Custom Properties section at the bottom of the filter dropdown. If it's still not there, add the property to at least one contact or wait for a form submission/import to populate it.

I'm trying to create a custom property during import, but I don't see the "Create New" option. What am I doing wrong?

The "Create New" option only appears when you start typing a custom property name that doesn't already exist. In the Map properties step, click the dropdown for the column you want to map, then start typing a new name (e.g., "loyalty_points"). If no existing property matches, you'll see Create New appear. Click it to create the property.

Can I Rename or Delete a Custom Property?

Custom properties cannot be renamed once created. However, you can delete a custom property from an individual contact’s profile.

If the property is collected through a signup form, you can either remove the related field (e.g., dropdown) or update its label. This ensures that new submissions are assigned to the correct property moving forward.