Identity

ShortKit assigns every device an anonymous ID on first launch. When your user signs in, you promote them to an identified user and the backend merges their anonymous history.

Anonymous by default

On first initialization, the SDK generates a random UUID and persists it in device storage. This ID is attached to every API request and analytics event automatically. No setup required.

Swift
Kotlin
Flutter
React Native
Web

// No user ID passed — SDK uses its auto-generated anonymous UUID.
let shortKit = ShortKit(apiKey: "pk_live_...", config: FeedConfig())

// Anonymous by default.
val shortKit = ShortKit(apiKey = "pk_live_...", config = FeedConfig())

// No userId passed — SDK uses its auto-generated anonymous UUID.
ShortKitProvider.apiKey(
  apiKey: 'pk_live_...',
  child: const ShortKitFeed(),
)

import { ShortKitProvider, ShortKitFeed } from '@shortkitsdk/react-native';

// No userId prop — SDK uses its auto-generated anonymous UUID.
<ShortKitProvider apiKey="pk_live_..." config={{}}>
  <ShortKitFeed />
</ShortKitProvider>

// Anonymous by default.
const sk = new ShortKit({ apiKey: 'pk_live_...' });

The anonymous ID survives app restarts. It is only replaced when you call clearUserId().

Setting an identified user

Call setUserId when the user signs in. The SDK switches all subsequent requests and events to this ID and triggers identity resolution on the backend.

Swift
Kotlin
Flutter
React Native
Web

shortKit.setUserId("user_abc123")

shortKit.setUserId("user_abc123")

final controller = ShortKit.of(context);
controller.setUserId('user_abc123');

import { useShortKit } from '@shortkitsdk/react-native';

function OnSignIn() {
  const { setUserId } = useShortKit();
  setUserId('user_abc123');
}

sk.setUserId('user_abc123');

You can also pass the user ID at init time to skip the anonymous-first flow entirely:

Swift
Kotlin
Flutter
React Native
Web

let shortKit = ShortKit(
    apiKey: "pk_live_...",
    config: FeedConfig(),
    userId: "user_abc123"
)

val shortKit = ShortKit(
    apiKey = "pk_live_...",
    config = FeedConfig(),
    userId = "user_abc123"
)

ShortKitProvider.apiKey(
  apiKey: 'pk_live_...',
  userId: 'user_abc123',
  child: const ShortKitFeed(),
)

import { ShortKitProvider, ShortKitFeed } from '@shortkitsdk/react-native';

// Pass userId prop to skip the anonymous-first flow.
<ShortKitProvider apiKey="pk_live_..." config={{}} userId="user_abc123">
  <ShortKitFeed />
</ShortKitProvider>

const sk = new ShortKit({ apiKey: 'pk_live_...', userId: 'user_abc123' });

Clearing identity

Call clearUserId on sign-out. The SDK reverts to anonymous mode with a fresh UUID. The previous anonymous ID is discarded.

Swift
Kotlin
Flutter
React Native
Web

shortKit.clearUserId()

shortKit.clearUserId()

final controller = ShortKit.of(context);
controller.clearUserId();

import { useShortKit } from '@shortkitsdk/react-native';

function OnSignOut() {
  const { clearUserId } = useShortKit();
  clearUserId();
}

sk.clearUserId();

How identity resolution works

When setUserId is called, the SDK sends a POST /v1/identity/resolve request with both the anonymous ID and the identified user ID:

{ "anonymousId": "a1b2c3d4-...", "userId": "user_abc123" }

The anonymous user profile is merged into the identified user profile, the anonymous device ID is appended to the identified user’s linked_device_ids array, and the anonymous profile is deleted. All events previously attributed to the anonymous ID become queryable under the identified user.

User ID on events

Every analytics event the SDK emits carries the current user ID in the X-User-Id request header — whether the user is anonymous or identified. You never need to attach user IDs to events manually. The SDK handles this at the network layer.

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Anonymous by default

Setting an identified user

Clearing identity

How identity resolution works

User ID on events

​Anonymous by default

​Setting an identified user

​Clearing identity

​How identity resolution works

​User ID on events

Anonymous by default

Setting an identified user

Clearing identity

How identity resolution works

User ID on events