Components of IDSync

Identity API

The identity API is used by all of mParticle’s SDKs to log users in and out of your app, to search for, and to modify a current user’s identities. It is also available as an HTTP API.

The identity API provides four endpoints for identifying users:

  • Identify - called when a session begins with whatever identifying information is available
  • Search - called to find current user identities or determine if a specific user exists
  • Login - called when a known user signs into the app.
  • Logout - called when a known user signs out

These four endpoints are called in response to different user actions, but they all perform the same function - resolving a request containing all known identifying information for the current user into a single, unique mParticle User Profile. That profile might be:

  • An existing profile that matches all identifying information in the request
  • An existing profile that matched some identifying information in the request, updated to include new information.
  • A new user profile, created when no existing profiles matched the request.

Identity strategies

Identity strategies determine which user profile to add data to when the current user can be identified, and what to do when the current user cannot be identified.

There are 5 identity strategies that have been designed to handle different business and privacy requirements.

Profile conversion

The profile conversion strategy is designed to help build a comprehensive picture of a user’s entire journey through a traditional sales funnel.

The main distinguishing feature of this strategy is that when a new login ID is received, IDSync will not create a new profile. Instead, it will simply add the new login ID to the previous profile used to store data collected when the user was anonymous.

Default identity strategy

The default identity strategy is a simplified version of the profile conversion strategy. The main difference is that the unique ID and login ID for the default identity strategy are set to customer_id, and they cannot be changed.

The profile link strategy is optimized to track the events that drive users to create an account or make purchases.

Profile isolation

The profile isolation strategy is built to prevent any anonymous data from being attributed to known users. This strategy is helpful when strict compliance with consumer protection and privacy regulation is required.

Best match

The best match strategy is not optimized to help uniquely identify users. It is best suited for businesses that do not have a login flow or that provide their primary services without requiring users to log in.

Identity priorities

Each identity strategy must define the order of precedence for matching user profiles. When an identity request is received, mParticle looks up matching profiles for each identifier in the order defined by the identity priority until a single profile can be returned. Keep in mind that some identity strategies impose minimum requirements that a request must fulfill in order to return a user even if they match (see Login Identities). For now, let’s just look at how the identity priority can affect which profile is returned by a request.


User profiles

Profile 1 Profile 2
IDFV: 1234
Other: AAAA
GAID: 2345
Other: BBBB


Identity Priority IDSync API Request Results
1. Customer ID
2. Email
3. Other
IDFV: 2345
Highest priority lookup (email) returns Profiles 1 and 2. Next highest priority (other) used as a tiebreaker. Profile 1 is returned. Other identifiers may or may not be updated based on the type of IDSync API request.
1. Customer ID
2. Email
GAID: 2345
Highest priority lookup (email) returns both Profiles 1 and 2. Next highest priority (IDFV) is not in the request, Following highest priority (GAID) used as a tiebreaker. Profile 2 is returned.

When Choosing your identity priority, ask the following questions about each of the identities you collect:

  • Is it an immutable ID? An immutable ID, such as Customer ID, must be the top rank identifier above all other IDs since it is a definitive customer identifier that is often shared across multiple apps or business areas in your organization.
  • Are they unique IDs? Unique IDs should be near the top of your hierarchy.
  • Do your customers use the ID to log in? Login IDs should also be near the top of your hierarchy.
  • Are they mutable? Some IDs may be changed by a user over time. Email is a good example.
  • Does it permanently identify a user? Some IDs are anonymous - cookies, device advertising IDs or other temporary IDs used for experimentation. Generally speaking, these should rank lower than IDs that permanently identify a user.
  • How likely are collisions for this ID? These should be ranked lowest in the hierarchy.

Feed specific user identifiers

There are some input feeds that always include a specific user identifier that you may or may not want to include in your identity priority list. To ensure that IDSync requests from one-off feeds like this can still be resolved even if you decided to omit their specific identifiers from your identity priority, you can configure an additional identifier for that specific feed without having to modify your overall identity priority.

If you ingest data from a feed with an extra identifier configured, mParticle still attempts to resolve any IDSync requests using your normal identity priority list first. Then, if no matching profiles are found, mParticle tries any additional identifiers configured for the feed. If a matching profile is still not found, then mParticle handles the anonymous user according to your identity strategy.

To configure additional user identifiers for a feed, contact your mParticle account representative.


For an example of how feed specific identifiers work, imagine the following two user profiles and stored identities:

Profile 1

  • IDFV: 1234
  • AID: 9876

Profile 2

  • Email:
  • GAID: 5678

Now imagine that we have the following identity priority list configured:

  1. Customer ID
  2. Email
  3. IDFV
  4. GAID

Let’s look at two scenarios where data is ingested from the same input feed with the same identity priority list described above.

Scenario 1: without a feed-specific user identifier

In this first scenario, data is ingested from the feed and an IDSync request is made for a user with the only identifier being an AID of 9876.

Since AID isn’t used in the identity priority and AID isn’t configured as a feed-specific identifier, IDSync fails to resolve the identity and the user is treated anonymously according to the identity strategy even though Profile 1 would be a match for the user.

Scenario 2: with a feed-specific user identifier

In the second scenario, AID is configured as a feed-specific identifier. Now, if the same IDSync request is submitted for a user with an AID of 9876, IDSync resolves the request to Profile 1. However, this will only be successful if the IDSync request is made for data ingested from the same feed that has AID configured as a specific identifier.

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