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
Adium is a versatile messaging client known for its extensive protocol support and customization, but its development has lagged. Kadu offers a lightweight and straightforward experience, focusing on simplicity and efficiency, but lacks some advanced features and customization options.