Identity Resolution ExternalIDs

NOTE: The steps in this guide pertain to spaces created before September 27th, 2020. For spaces created after September 27th, 2020, please refer to the onboarding guide here.

Default ExternalIDs

The Identity Graph creates or merges profiles based on externalIDs. ExternalIDs will become the Identities attached to a User Profile in the User Explorer:

Segment automatically promotes the following traits and IDs in track and identify calls to externalIDs:

External ID Type Message Location in Track or Identify Call
user_id userId
email or when context.device.type = ‘android’
android.idfa context.device.advertisingId when context.device.type = ‘android’ AND context.device.adTrackingEnabled = true
android.push_token context.device.token when context.device.type = ‘android’
anonymous_id anonymousId
braze_id context.integrations.Braze.braze_id when Braze is connected as a destination
cross_domain_id cross_domain_id when XID has been enabled for the workspace
ga_client_id context.integrations[‘Google Analytics’].clientId when explicitly captured by users
group_id groupId when context.device.type = ‘ios’
ios.idfa context.device.advertisingId when context.device.type = ‘ios’
ios.push_token context.device.token when context.device.type = ‘ios’

Custom ExternalIDs

Personas will automatically resolve identity for any other externalIDs that you bind to users - such as a phone number or any custom identifier that you support. As seen in the below example, you can send custom externalIds in the context object of any call to our API.

The four fields below (id, type, collection, encoding) are all required:

Key Value
id value of the externalID
type name of externalID type (app_id, ecommerce_id, shopify_id, etc)
collection users if a user-level identifier or accounts if a group-level identifier
encoding none

As an example:

analytics.track('Subscription Upgraded', {
   plan: 'Pro',
   mrr: 99.99
}, {
  externalIds: [
      id: '123-456-7890',
      type: 'phone',
      collection: 'users',
      encoding: 'none'

Personas will automatically create a user (user_id: use_123) with the custom externalId (phone: 123-456-7890). Then, you query the users phone record by using the external id (phone: 123-456-7890), or update this profile using that externalId going forward. (Note: externalIDs must be lower-case.)

Viewing Promoted ExternalIDs

Users can view which externalIDs are promoted on each event by viewing the raw payload on Events in the User Profile in the “external_ids” object.

For example, the following user had anonymous_id and user_id promoted as identifiers from the Course Clicked track call:


For example, a new anonymous user visits your Pricing page:'Pricing', {
  anonymousId: 'anon_123'
  title: 'Acme Pricing',
  url: '',
  referrer: ''

At this point, the Identity Graph will create a new user with external id (anonymous_id: anon_123) and a persistent and globally unique segment_id, in this case: use_4paotyretuj4Ta2bEYQ0vKOq1e7.

Any new events received with the same external id (anonymous_id: anon_123) are appended to same user use_4paotyretuj4Ta2bEYQ0vKOq1e7.

Next, the user goes to a sign up form and signs up:

analytics.track('User Signup', {
  userId: 'use_123',
  anonymousId: 'anon_123'

At this point, the Identity Graph associates external ID (user_id: use_123) with the same user use_4paotyretuj4Ta2bEYQ0vKOq1e7.

This page was last modified: 06 Nov 2020

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