Is there a group chat feature?
A group chat feature (up to 50 group members) is available in the app. Group chats are handled on each individual device. The Threema servers have no knowledge about group compositions.
New groups can be created using the Floating Action Button in the contact list (on Android), the “Compose message” button (on iOS), or “New group chat” (on Windows Phone). Only those contacts can be selected from the list that have installed a group chat capable version of Threema.