Google Calendar Alternatives for Linux

Lightning is a comprehensive calendar and task management add-on for Mozilla Thunderbird and Seamonkey, designed to integrate seamlessly with email. It offers robust features for scheduling, task tracking, and synchronization with various online calendar services, enhancing productivity directly within your email client.

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.

Kolab Community is a comprehensive, free, and open-source groupware suite designed for collaborative work. It provides integrated email, calendar, contacts, and tasks functionalities, empowering individuals and teams to communicate and manage their data efficiently and with a strong focus on data privacy.

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.

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.

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.