Custom Properties store contact data permanently and work across all campaigns and automations. Custom fields attach to events and are available only in automations triggered by those events.
Continue reading to learn more about the key differences between custom properties and custom fields.
Custom Properties
Custom Properties are data fields stored in each contact's profile. Examples include loyalty points, membership tiers, or any other detail unique to that contact.
You can collect custom properties through:
Signup forms: Add custom fields (e.g., interests) to your forms. When contacts submit the form, their responses are saved as custom properties.
Manual entry: Go to Audience → Contacts, open a contact, and click Edit Contact to manually add or update custom properties.
Contact import: Upload a CSV file with contact emails and additional data columns. Omnisend maps each column to a custom property during import.
API or integrations: Third-party apps (e.g., loyalty programs, CRMs, ecommerce platforms) can pass custom properties via API when contacts are created or updated.
Locating Custom Properties
To view custom properties, go to Audience → Contacts, search for the contact by email or phone number, click to open the profile, and find the Custom Properties section in the left-hand menu.
Using Custom Properties
As custom properties are saved directly to the contact profile, you can use them to:
Personalize message content in campaigns and automations;
Create audience segments based on contact personal data.
💡 If a third-party app passes custom property data through the API, you can review the request payload in Store Settings → API → API Logs.
Custom Fields
Custom fields (called event properties in the API documentation) are event-specific data passed with Custom events. They describe the details of a specific action, such as a tracking number, product name, or event timestamp.
Think of it this way:
A custom event is the action itself (e.g., Order Shipped, Webinar Registered, Review Submitted).
Custom fields are the details related to that specific instance of the action (e.g., which product shipped, which webinar, what review type).
Example:
When your store sends a Review Submitted event to Omnisend, it might include the following custom fields:
rating:"3 stars"productId:"1Z999AA10123456784"comment:"this product felt amazing!"reviewDate:"2026-01-20"
These details apply only to that single review for that specific contact at that moment.
Note: In the API documentation, custom fields are referred to as "event properties." Once synced to Omnisend, they appear in the product UI as "custom fields." Both terms describe the same data: the event-specific details passed with each custom event.
Locating Custom Fields
You can review which custom fields are passed with each custom event by going to Store Settings → API → Custom Events. This section displays a full list of your custom events along with the custom fields included in each one.
Unlike custom properties, custom fields are not permanently saved to the contact profile.
To view them, open the contact profile, select the event from the drop-down menu in contact activity. Click the three-dots (⋮) next to the event, then select Event details. This view shows all the data passed with that specific custom event.
Using Custom Fields
Custom fields can be used in multiple ways within automations and segmentation:
Automation trigger filters - After selecting a custom event as the trigger in your workflow, available custom fields will appear in the trigger filters dropdown.
Automation split rules - Use custom fields to create split blocks in your workflow.
Message personalization in automations - Custom fields can be inserted into messages using personalization tags (e.g.,
[[event.trackingNumber]]). This applies to automation workflows only, not campaigns.
Segments - After selecting the custom event as the main filter in your segment, custom fields become available as subfilters.
Key Aspects
Custom properties and custom fields may appear similar, but they serve very different purposes within Omnisend. Here's what you need to know:
Both custom properties and custom fields can be used in message content via the Personalization menu in automation workflows. However, only custom properties can be used in campaigns.
Custom fields are tied to the specific custom event they are passed with. They are temporary, apply only at the time the event is triggered, and are only available within the automation triggered by that event.
You cannot use custom fields as standalone segment rules. They can only be used as subfilters within a custom event condition when building segments.
Custom properties are stored and permanently visible in the contact profile. They can be manually edited, imported, or updated through forms, API, or integrations.
Custom fields are not visible in the contact card unless you open the event details from the contact's activity timeline.
FAQ
Can I use custom fields in campaigns?
No. Custom fields are available only in automations triggered by the custom event that passes them.
Where do I see which custom fields exist?
Go to Store Settings → API → Custom events. Click on an event to view its custom fields.
If you still have any questions or need assistance, please contact us at [email protected] or via in-app chat.