WhatsApp is encrypted end-to-end, so the contents of the messages can't be seen. One such app has been found that allows users to collect information about their WhatsApp contacts - or have it collected about them. It uses this to tell people how often you check the app and roughly when you bed down for the night. According to tech site The Next Web , the app will find this data even if you've disabled WhatsApp's "Last Seen" feature in your settings. The app appears to have been removed from both Apple's App Store and the Google Play Store which serves Android devices.

Source: Daily Mirror March 30, 2018 10:57 UTC