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
Pidgin is a versatile instant messaging client with extensive protocol support and customizable features, making it suitable for advanced users. Kadu, on the other hand, offers a simpler interface and is more suited for users looking for basic messaging without the complexity.