Kadu is a free and open source multi-platform instant messaging client that supports Gadu-Gadu, XMPP IM networks and other services based on XMPP like Google Talk. Developed by KaduTeam
License: Open Source
Psi is a robust and highly customizable XMPP client, suitable for users who need advanced features and multi-account support. In contrast, Kadu is more user-friendly and lightweight, making it ideal for casual users who prefer simplicity.