User Attributes

The SDK surfaces a series of APIs to associate “attributes” with a user. Attributes can be any set of free-form keys and values. It’s important to understand the following before reading on:

  • The SDK maintains a “current” user in tandem with usage of the IDSync APIs, which you can read more about here.
  • On first SDK initialization, there is no current user and the APIs below will return null
  • Once the SDK has successfully called the IDSync identify API for the first time, you will be able to access the current user via the mParticle User object
  • Any events recorded prior to the first IDSync API call will be associated with the first user. The SDK will not upload data until the first IDSync API call has returned.

mParticle ID

All users are associated with a signed 64-bit integer called the mParticle ID (MPID). On the web, this is surfaced as a string due to the limitations of the Javascript number type. Note that this value may be negative. Many mParticle integrations can map the MPID as the external user id for the given integration. MPIDs are shared across browsers and devices depending on your IDSync strategy and usage of the IDSync API.

Current user

The SDK maintains a “current” user and will associate all events with the current user at the time that they occur. There are several ways to retrieve a reference to the current user object.

Direct Query

Query the SDK directly for the current user. Note that on first page load this may be null.

var currentUser = mParticle.Identity.getCurrentUser();

IDSync API Result

Whenever an IDSync API is invoked, the callback for a successful request will will be invoked with a reference to the new user object. See the IDSync page for more information. Note that depending on your IDSync strategy, the MPID (and therefore the current user) may not change for every IDSync API call, such as for new user registration (login) scenarios.

Set User Attributes

User attributes are free-form key-value pairs. The underlying mParticle events API only accepts three types of values: strings, lists, and the JSON null sentinel in the case of tags.

// Note: may return null if the SDK has yet to acquire a user via IDSync!
var currentUser = mParticle.Identity.getCurrentUser();

// Set user attributes associated with the user 

// You can change the value of an existing attribute at any time
currentUser.setUserAttribute("top_region","North America");

// Associate a list of values with an attribute key
currentUser.setUserAttributeList("destinations", [
    "San Juan",

// Remove attribute - 
// all attributes for a given user share the same key space,
// you cannot have lists, tags and regular attributes with the same key

Set User Tags

A tag is a label or category to which a user belongs. While the SDK sets a tag as a string, mParticle’s master data structure defines attributes as a map, so tags are stored with a null value. For example, when you set the "platinum_member" tag on a user, the user profile will get the attribute "platinum_member": NULL.

// Set tag
// Note: may return null if the SDK has yet to acquire a user via IDSync!
var currentUser = mParticle.Identity.getCurrentUser();

// Remove tag

Reserved Attributes

Below is a list of mParticle “reserved” user attribute keys. Several integrations use these keys for deterministic data mapping:

  • $Age
  • $FirstName
  • $LastName
  • $Gender
  • $Mobile
  • $Address
  • $City
  • $State
  • $Zip
  • $Country

Attribute Key Limitations

Always refer to your organization’s data plan when instrumenting user or event attributes. Each unique attribute key becomes a data point in the mParticle user interface that can be filtered for each output, used to drive the calculation of an audience or become part of a custom mapping. This means that your choice of attribute keys can have a system-wide impact. For example, if you have a single attribute key per device that represents a unique user ID or a unique URL, and you have thousands of users, mParticle will see thousands of unique keys, even though you only create one per device.

Creating too many unique attribute keys can have several adverse effects:

  • The mParticle dashboard becomes overcrowded and it becomes harder for business users to manage individual data points
  • Each individual data point can be switched on or off as a data filter. If you filter data to kits, this filter information is downloaded by the SDK during your app’s initialization. The more unique data points you have, the larger the size of the download. If not controlled this can ultimately impact the performance of your app.
  • A high number of unique attribute keys makes it difficult for you to use mParticle features like rules and audience builder to control your data flow.

You should avoid the following as attribute keys:

  • URLs
  • Dates
  • Dynamic strings
  • User IDs
  • Random IDs


A gaming app has ten levels and you want to track which level each user has achieved. Rather than creating ten tags such “reachedLevel1”, “reachedLevel2”, it is better to create a single attribute “reachedLevel” and use the value as the level.

Capturing this data as a single attribute improves the performance of both your app and the mParticle dashboard by reducing the number of unique data points you need to manage. It’s also a much more useful data point. For example, you can easily create a single audience builder condition to target users within a range of levels reached.

Cross-Platform Attribute tracking

An mParticle workspace can combine data from multiple platforms, for example it can show data from your web and android app. For this reason, you may wish to choose attribute names that you can keep consistent across all platforms for easier management. For example, if you call an attribute levelReached in iOS, LevelReached on Android, and level_reached on web, mParticle will treat these as three separate attributes.

Integration Attributes

Several partner integrations expect custom keys and values associated with each user or device, known as integration attributes. These are similar to “custom flags” except rather than being specific to an event, they’re specific to a user or device. The most common example of this are partner-specific user or device IDs.

The web SDK will persist any integration attributes at the device-level (rather than user-level), and will include them with every event upload. You can set an integration attribute by specifying an integration ID as well as a key and value:

//update the partner ID and attribute key as necessary for your integration
var adobePartnerId = 11;
var adobeVisitorIdAttributeKey = "vid";

var integrationAttributes = {};
integrationAttributes[adobeVisitorIdAttributeKey] = "<Adobe Visitor ID>";
mParticle.setIntegrationAttribute(adobePartnerId, integrationAttributes);

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