WhatsApp offers a "Contact Upload" feature, allowing you to grant the app access to your phone's address book. WhatsApp then securely uploads hashed versions of your contacts' phone numbers to its servers. This enables WhatsApp to identify which of your contacts also use the service, helping you connect with friends easily. WhatsApp explains it does not store your full address book or share it with third parties, using the hashed data solely for contact discovery purposes.
Device Information for Performance Optimization
WhatsApp continuously whatsapp data collects detailed device information to optimize app performance. This includes data on your phone's model, operating system version, screen resolution, and available storage. This information helps WhatsApp tailor updates, bug fixes, and feature rollouts to specific device types, ensuring compatibility and stable operation. It also assists in diagnosing app crashes and performance bottlenecks, leading to a smoother and more reliable user experience across the vast array of devices running WhatsApp.