Etar - OpenSource Calendar was until recently, my primary calendar because it supports Calendaring Extensions for WebDAV ("CalDAV")... And in this respect, Etar - OpenSource Calendar still works quite well. I have however, switched to Simple Calendar (also Open Source) because it requests access to fewer permissions and I prefer the design. This is not to say that Etar - OpenSource Calendar is a bad application, just that I prefer Simple Calendar. If you want something to replace Google Calendar or whatever came with your mobile device, my first recommendation would be Simple Calendar, followed closely by this... But don't take my word for it - install both and see which you prefer!

Easily the cleanest and most functional calendar app I've used so far. Ability to simultaneously display a second date other than the Gregorian like Hijri or Hebrew would be great!

Smart looking and effective calendar app. Syncs with all my various Google calendars.

Etar is a straightforward open source calendar. It works like the AOSP calendar with the ability to write in events and sync to other services. The additional features compared to the stock AOSP are a cleaner design and some night mode features for those who want it. Overall it's an easy to use calendar with a clean design that works like the AOSP calendar.

Great Application. Works with Davdroid/CalDav to connect to Owncloud/Nextcloud server. I can now disable the stock google calendar application. I like the "agenda" view and the simplicity of the application. I am a heavy user of my calendar application on my phone to stay organized. Thanks to all the developers!!!

Clear, simple, like a calendar has to be. Just one feature is missing: the icon should show the current day rather than always 30 - like on my Palm Pre :-)