Google Calendar Alternatives for Linux

Calendar encryption: View calendars and stores them encrypted on your device or in the cloud.

Organize your schedule and life’s important events in a calendar that’s fully integrated with your Thunderbird or Seamonkey email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.

Rainlendar is a feature rich calendar application that is easy to use and doesn't take much space on your desktop. The application is platform independent so you can run it on all major operating systems: Windows, Linux and Mac OS X.

Morgen merges your calendars, to-dos, productivity apps, and schedulers, so you manage all your time in one place. With Morgen as your time management hub, you’ll stop wasting time flipping between calendars, apps, and browser tabs, and just get work done.

fruux is a free service that takes care of your contacts, calendars and more so you don't have to. Never manually copy contacts and calenders between your devices again!

Personal Information Manager (Mail, Contact, Calendar and more).

Kolab is entirely Free and Open Source Software (a.k.a. FOSS), and uses Open Standards. We’ll get to why this is important to us, and hope that it is important to you thereafter.

Kalendar is a Kirigami-based calendar application that uses Akonadi. It lets you add, edit and delete events from local and remote accounts of your choice, while keeping changes syncronised across your Plasma desktop or phone.

woelkli is a service that provides secure cloud storage hosted in Switzerland. Save, view, edit and share your files from anywhere in the world, from any device

It provides management of events and tasks, alarm notification, web export, network transparent handling of data, group scheduling, import and export of calendar files and more. It is able to work together with a wide variety of calendaring services, including NextCloud, Kolab...