A bunch of calendars only work when connected to the internet. Others don’t sync across multiple types of devices (linux, android, apple, etc).
A lastpass of calendars, but open source.
Fwiw The GNOME Calendar app has served me well. It has syncing capabilities.
The calendar that comes with Ubuntu Touch is also very good - I don’t know whether it’s available to download to other platforms though.
And there used to be a really nice ToDo / calendar combo, called NitroTasks… but I don’t know it’s status any more.
OT: Ubuntu Touch is such an awesome mobile OS. The usability and the focus on gestures feels so much more natural than Android. Also the Qt Quick applications fit really well into the environment. I wish it was used more widely.
:) I agree completely.
Tutanota calendar is okay.
It doesn’t have offline support.
You may want to try DecSync
This is what I use, it works really well.
You can sync calendars that support CalDav pretty easy to most devices. I am using a Nextcloud instance as server^1 for the calendar and synchronize it to my android phone via DAVx5. GNOME desktop/calendar also has support for CalDav and Lightning (Thunderbird’s inbuilt calendar tool) too. For terminal there is khal + vdirsyncer.
^1 some mail provider such as posteo.de or mailbox.org also provide a CalDav calendar for their plans.
CalDAV (+CardDAV) is the easiest solution. Evolution mail works great as a desktop client too. DAVx5 will integrate into your android calendar and contacts seamlessly. If nextcloud is to fat for you there is also DAViCal (php+postgres) and radicale (python…).
Sadly there are no clients that encrypt your data :/
