GB WhatsApp is a modified version of the WhatsApp Messenger app for Android devices. It is developed by a third-party developer and is not officially endorsed by WhatsApp. The app adds additional features and customizations that are not available in the official version of the https://gb-whats.app/. Some examples of these additional features include the ability to run multiple WhatsApp accounts on the same device, hiding the "last seen" timestamp, and the ability to use custom themes and fonts.