Set Customer User ID

AppsFlyer Customer User ID (CUID) is a powerful feature that allows you to associate your internal user identifier with attribution and event data sent from the SDK or by server-to-server (S2S) requests. This is especially valuable for:

• Connecting AppsFlyer data with your own user databases.
• Enabling deterministic matching across platforms and sessions.
• Supporting deep analysis, re-engagement, and LTV modeling.
• Unlocking advanced cross-platform analytics and deduplication.

To properly use the CUID feature, the value must be set before the SDK sends any event to AppsFlyer. Therefore, retrieving or generating the CUID at the right time in the app lifecycle is crucial.

Below is a platform-by-platform guide for retrieving and setting the CUID across all supported SDKs. Each link below leads to the dedicated section in the respective documentation:

CUID Integration Guides by Platform

• Android
• iOS

Steam

• Unity Steam
• Unreal Steam
• Steam C++

Epic

• Unity Epic
• Unreal Epic
• Epic C++

Meta Quest (Oculus)

• Meta Quest 2 Unity
• Meta Quest 2 Unreal

Native

• Native PC Unity
• Native PC Unreal
• Native PC C++

CTV

• Roku (BrightScript)
• LG Webos
• Samsung Tizen

Mobile Plugins

• Unreal mobile plugin
• Unity Plugin

Server to Server (S2S)

• PC/Console/CTV Events
• Web
• Mobile

Additional

• Google Play Games on PC - identical to Android