My network includes a CalDAV calendar hosted on Baïkal. It allows me to share a calendar between my desktop (Linux and Thunderbird) and my Android phone running OneCalendar. The devices sync automatically when they are both connected on my home network.

Baïkal and Thunderbird both support tasks, but OneCalendar does not. I would like to add this functionality to my phone (a Samsung Galaxy S10 with Android version 12), so I am seeking a CalDAV to-do app for Android; or a combined calendar and task manager.

This question on Android Enthusiasts, How do I manage CalDAV-provided tasks? seems to be a duplicate, but the accepted answer OpenTasks will not install for me.

I have read lots of product descriptions and reviews, but it is rare to see CalDAV mentioned. Many boast about Google Calendar, but I prefer to keep my data under my control and will not use a cloud solution.

I have tried these:

  • OpenTasks, but it requires an old version of Android
  • DAVx⁵ could not connect to my server. It said: “This app is for organisations and not for private users.”
  • Syncthing-Fork only seems to sync with other Syncthing installations.

Before I waste lots of time trying other apps where the description is incomplete, I would like to hear from anyone who has experience of CalDAV tasks.

Please let me know of any useful knowledge in this area.

  • I use DAVx⁵ with my Nextcloud for years and have never seen that error message. Where did you install it from? They have 2 different versions, one for organizations ("Managed DAVx⁵") and one for "private users" – maybe you've picked the wrong one? The one I use is this one from F-Droid, which is also available at PlayStore.
    – Izzy
    Commented Oct 22, 2023 at 10:31
  • @Izzy The F-Droid versions seem better. I now have DAVx⁵ working. I'm not there yet, but your comment is a big help. Please rewrite your comment as an answer, ideally with suggestion(s) for a tasks app (I am looking at jtx Board).
    – Peter Bill
    Commented Oct 22, 2023 at 15:42
  • I most exclusively use my apps from F-Droid (disclosure: I'm also one of the maintainers there) – & I can say your statement holds true for some other apps as well ;) But while I could write a recommendation for DAVx⁵, I don't use any tasks app & thus could not include that. Though once sync'd to your device, I guess all task apps (as long as they use Android's calendar storage) should pick them up. You can find a selection on my website to pick from. Tasks.org seems to fit.
    – Izzy
    Commented Oct 23, 2023 at 17:54
  • Actually, reading the description and checking the screenshots of Tasks.org, it seems it can sync with CalDAV on its own even, so maybe take a look at that first (while I update that to its description at above linked app listing).
    – Izzy
    Commented Oct 23, 2023 at 17:57

2 Answers 2


Personally I really have to recommend Singularity on the android playstore. It has that and more. Projects, habits, tasks, calendar -all incorporated together however you choose. It's my dream-come-true app. I don't, but my brain hates all other task, calendar, journal, habit, and project apps for some reasom besides Notify for notes]. All other apps seem to consistently not be up to my liking / standards or work for me.

The only thing I would change in the Singularity app would be switching the checklist and note section in Projects, but that's just Projects fortunately. Otherwise, I absolutely adore it.

Hopefully I didn't misundetstand your post about it simply needing to have a calendar feature [not one that syncs specifically with one the one you already have -though it might, or they might implement it for you since they're new and very customer oriented]. It syncs with Google calendar, but I think I remember there being another calendar option, for "other calendars" .

Oddly, the app also syncs with telegram and email, as to create a telegram message or email to 'quickly create a task'. Personally, I'll just be using the app to do that. I haven't used a task app in years until this one. There's also a website for it to in case that matters.

Hope you find it as helpful as I have! Or, eventually find one that's as helpful as Singularity has been for me! Sorry about the anonymous answer. Im having an issue logging in.

  • Not sure what to make of this answer. It's like a cross between an ad and a rant. There's not even a link to the app. The only Singularity I could find seems to be something else. If you wish to be taken seriously, please remove the gushing and the reference to Google (as per OP, it is out-of-scope), and add some references.
    – Peter Bill
    Commented Oct 23, 2023 at 8:40

Thanks to @Izzy for the suggestions in Comments.

I installed DAVx⁵ from F-Droid (this version is free, unlike the Play Store version). It was easy to create an account linking to my Baïkal server.

DAVx⁵ had a couple of suggestions for the task app. I chose jtx Board which seems to work well. It’s more feature-rich than I anticipated, but I’m sure I will use the other features.

  • I've just discovered that i can 'Share' an SMS with jtx Board. After a sync, it appears in Thunderbird as a Task.
    – Peter Bill
    Commented Feb 1 at 11:35

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