Understanding identity resolution in Klaviyo

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Learn about identity resolution in Klaviyo, which consolidates customers’ interactions across multiple channels under a single record.

Since Klaviyo is an omni-channel marketing tool that supports email, SMS and mobile push notifications, your customers may interact with you through either or all of these channels. To ensure that your customer profiles remain up-to-date with activity across all these channels, Klaviyo automatically resolves the identities of different profiles that share a common identifier based on the existing data in your account.

What is identity resolution? 

Identity resolution refers to the ability to maintain a single customer record, even when a customer’s engagement uses different combinations of identifiers over time. This provides a unified view of your customers regardless of their engagement channels. 

A common example of this is when a customer that has an email profile in your Klaviyo account later subscribes to SMS through a method that is not associated with their email, like a keyword opt-in. This customer action results in a separate profile for receiving SMS messages. However, if this customer later takes an action like making a purchase where they submit both their phone and email; Klaviyo will recognize that both the phone and email belong to the same customer and their profiles will be merged.

Klaviyo’s identity resolution functionality has 2 key components: 

  • Identity capture
    Klaviyo’s identity capture functionality automatically cookies and identifies users that click through your email or submit a Klaviyo form, allowing you to capture your customer’s every engagement with you.

  • Deterministic profile merge
    Klaviyo resolves customer identities through a proactive check that merges two separate profiles when an action occurs linking an email address, phone number, or device ID (iOS) together. This allows you to effectively manage omnichannel customer data. 

How identity resolution works in Klaviyo

As customers interact with your brand across different channels, Klaviyo checks for opportunities to merge these engagements under a single customer profile. 

This is based on a process called "identifier precedence,” where Klaviyo uses existing data to determine if these omni-channel engagements can be consolidated under a single, stronger identifier.

Klaviyo ranks these identifiers as:

  1. Profile ID
    The primary identifier Klaviyo assigns to each profile. 
  2. External ID
    An external ID that can be used as a primary identifier on the profile, typically in place of an email address. External IDs are set through some integrations (e.g. Bigcommerce), or through Klaviyo’s APIs. 
  3. Email
    The email address associated with a profile. 
  4. Phone number
    The phone number associated with a profile. 
  5. Anonymous mobile app ID
    For mobile app profiles, if Klaviyo cannot associate the user with an email address, an anonymous mobile app ID will represent the iOS profile. 

For each lower-ranking identifier, Klaviyo checks if a profile exists within the account recognized only by that identifier. If such a profile is found and can be associated with a higher-ranking identifier based on an instance where they were linked together, Klaviyo will attempt to merge under the higher-ranking identifier. 

To illustrate this, below is an example where Klaviyo is resolving the identity of a customer with the following set of identifiers: 

Identifier type Value



Phone number 


Anonymous mobile app ID 


Once Klaviyo sees all 3 identifiers together, which indicates they all belong to the same customer, it will check if there is a profile only identified by phone number or only identified by an anonymous mobile app ID. If either are found, they will be merged into the profile with the higher-ranking identifier, in this case email. 

Data that triggers a profile merge

For Klaviyo to identify that multiple profiles belong to the same customer, the identifiers associated with each profile need to be recognized together. Often, this information comes in the form of an event, where the event data includes multiple identifiers like email and phone number. Klaviyo also merges profiles based on data that customers submit themselves (e.g., through a form that has fields for both phone and email).

Klaviyo merges profiles based on information submitted through web tracking as well, which associates an activity to an email profile using cookies. For example, if an email profile submits a phone-only form with their cookie present, then the phone number they submit will be appended to their pre-existing profile. 

Actions related to click-to-text or keywords will generally not result in a merge based on cookie tracking. This is because the cookie trail is lost across applications (e.g., web to SMS) and we cannot be certain that the 2 actions were taken by the same person.

Find a profile ID

Every profile has a unique ID that you can find by navigating to the profile and looking at the URL. Look for the 26-character ID, as illustrated in the image below.

24 character profile ID in the URL of a profile

Some older profiles in your account may have a six-character ID if you acquired them prior to this Klaviyo change. This ID is still correct and unique to their profile. 

6 character profile ID in the URL of a profile

Manually merge profiles

If you know that a pair of profiles belongs to a single customer, you can manually merge the two. Merging a pair of profiles will result in only one profile, with one email address, for the contact. The customer ID of the most recently updated profile will be maintained.

Note that merging profiles cannot be reversed.

To manually merge a profile: 

  1. Navigate to the source profile you want to remove. 
  2. Scroll to below the Information section.
  3. Click Merge Profile.
    Merge button on a profile
  4. In the pop up that appears, type the email address or name of the destination profile you want to merge into (i.e., keep). Then hit the Return or Enter button on your keyboard to search.
  5. Select a profile from your search results. If you don’t see the destination profile you’d like to merge into, make sure there are no typos in your search. Then hit the Return or Enter button to search again.

For more information, head to our guide on how to delete, merge, and export a profile.

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