Kopete is a multi-protocol, free software instant messaging client released as part of the KDE Software Compilation. Although it can run in numerous environments, it was designed for and integrates with the KDE Plasma Workspaces. Developed by kde.org
License: Open Source
Adium is a versatile messaging client focused on macOS users with extensive plugin support, while Kopete is designed for Linux users with good integration into the KDE environment. Both applications support multiple messaging protocols but differ in platform compatibility and maintenance status.