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Version: v2

Identify Users

Identify a user.

Each time a page loads for a user you can identify, you'll want to call the FS('setIdentity') function to associate your own application-specific id with the active user.

Type annotations for properties are no longer required. See Custom Properties.

    uid string required

    A string containing your unique identifier for the current user.

    properties object optional

    A JSON object with key/value pairs that provides additional information about your user.

    schema object optional

    A JSON object with key/value pairs that provide explicit type inference for your properties. See Custom Properties.


Fullstory doesn't let you change the identity of a user once they have been assigned a unique user ID using FS('setIdentity'). If you attempt to change the user id of an identified user, Fullstory will recognize the new user ID and automatically split the session into a new session.


  • Sustained calls are limited to 30 calls per page per minute with a burst limit of 10 calls per second.

Additional Information

FS('setIdentity', { uid, properties })

Example Invocation

FS('setIdentity', {
uid: '462718483',
properties: {
displayName: 'Daniel Falko',
email: '',
custom_field: 1