Trillian is described as «instant messaging app that works on phones, tablets, and desktops while keeping your chats neatly synchronized between all of them! We think conversation should be easily shared between all of your devices, not trapped as text messages on your phone» and is a very popular instant messenger in the social & communications category. There are more than 100 alternatives to Trillian for a variety of platforms, including Windows, Linux, Mac, Android and iPhone. The best alternative is Signal, which is both free and Open Source. Other great apps like Trillian are Element, Pidgin, Tox and Zulip.Trillian alternatives are mainly Instant Messengers but may also be Group Chat Apps or Encrypted Chat Apps. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of Trillian.