Linux Softwares to Automatic Duplicate Merge

fruux is a robust cross-platform synchronization service designed to keep your contacts, calendars, and tasks seamlessly in sync across all your devices and applications. It offers a secure and reliable cloud platform with strong privacy focus, ideal for individuals and teams needing consistent data access and collaboration.

Memotoo is a comprehensive online service designed to centralize and synchronize all your personal information, including contacts, calendars, tasks, notes, and bookmarks. It acts as a hub to connect various online services and devices, ensuring your data is consistent and accessible from anywhere.

Kontact is a comprehensive personal information management suite from KDE combining email, contacts, calendar, tasks, and news in one integrated application. It offers robust synchronization options and supports various protocols.