Pidgin is a free and open-source chat client which supports AIM, Google Talk, ICQ, XMPP protocols. Developed by Pidgin
License: Open Source
Quassel IRC is designed for users who prefer a persistent connection and multi-channel support, making it ideal for long-term IRC use. Pidgin, on the other hand, is a versatile multi-protocol instant messaging client, focusing on ease of use and extensive plugin support, making it suitable for users who want to connect to various messaging networks.