Kontact Alternatives for Linux

Rainlendar is a highly customizable calendar application for Windows, macOS, and Linux. It seamlessly integrates with popular online calendars like Google Calendar and Fantastical, offering comprehensive event and task management directly on your desktop.

Sylpheed is a free and open-source email and news client known for its lightweight design and speed, focusing on usability and efficient handling of large email collections without burdening system resources.

Mutt is a highly configurable, text-based email client for Unix-like systems. It offers powerful features for advanced users who prefer a lightweight and efficient email management experience directly from the command line.

Zimbra Desktop provides a unified interface for managing multiple email accounts, calendars, tasks, and contacts offline. It supports various protocols like IMAP, POP, CalDAV, and CardDAV, offering a comprehensive personal information management solution.

OpenProject is a powerful, web-based open-source project management software designed for teams of all sizes. It offers comprehensive tools for managing projects, tasks, teams, and communication in one centralized platform. Ideal for organizations prioritizing collaboration, flexibility, and data control.

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.

KOrganizer is a comprehensive calendar and scheduling application, part of the integrated KDE Kontact suite. It provides robust tools for managing events, tasks, and deadlines, with extensive connectivity options and customization.