User Identifier and Property

Managing User Identifiers

User identifiers are used to uniquely identify different users.
Refer to the Managing User Identifiers document for an in-depth definition and understanding of why user identifiers are so important during experimentation.

Use SDK-managed identifiers

The React SDK includes features to automatically manage device identifiers. Therefore, the user can be automatically identified without having to manually pass the user identifier separately as a parameter.

Use custom user identifiers you manage

This is a method of directly passing a user identifier as a parameter. The identifier to be delivered can be a directly managed primary key, device identifier, member ID, email, hash value, etc.

Using User Identifiers in an SDK Initialization Example

// 1. Using SDK-managed identifiers - do not pass user identifiers in parameters
<HackleProvider hackleClient={hackleClient}>
  <YourApp />

// 2. Using user identifiers managed yourself - pass user identifiers in parameters
const user = { 
  id: "ae2182e0"

<HackleProvider hackleClient={hackleClient} user={user}>
  <YourApp />

Additional Identifiers

In addition to the default identifier, additional identifiers can be sent through the example code below.

const user = {
  id: "ae2182e0", // Default identifier provided
  userId: "143", // User ID (Hackle integrated identifier supported)
  deviceId: "ae2182e0", // Device ID (Hackle integrated identifier supported)
  identifiers: {
    myCustomId: "42" // Custom ID


Hackle SDK supports adding properties to a User object.

  • Properties must be sent as a pair with both property name (key) and a property value (value).
  • The maximum number of properties that can be added to a User object is 64.

Property Key (Name)

  • The key should be set as a general name, but easily identifiable.
  • The character limit is 64 characters.
  • It is not case sensitive. For example, AGE and age are recognized as the same key.

Property Value

  • The value supports boolean, string, and number types.
  • In the case of string type, the character limit is 64 characters.
  • The string type is case-sensitive. For example, APPLE and apple are recognized as different property values.
  • In the case of number type, up to 15 integers and up to 6 decimal places are supported.


The User object is used as a parameter when initializing the SDK.

Refer to the example code and add the desired properties to each user. In the example below, you can see that three properties (age, grade, is_paying_user) have been added.

const user = {
  id: "ae2182e0",
  properties: {
    age: 30,
    grade: "GOLD",
    is_paying_user: false

<HackleProvider hackleClient={hackleClient} user={user}>
  <YourApp />