Is there a group chat feature?
A group chat feature is available. Group chats are handled on each individual device. The Threema servers have no knowledge about group compositions. In Threema, groups can contain up to 50 members; in Threema Work, groups can contain up to 100 members.
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.