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Calendula, Etar, or Fossify Calendar?

I wrote one of these three, so read this with that in mind. What I can offer instead of impartiality is that every claim below about the other two is checked in their source rather than taken from their marketing — and that I will tell you plainly when one of them is the better answer for you.

The short answer

  • Pick Etar

    If you want it proven

    • Your phone is on Android 6 to 9
    • You want the most tested of the three
    • Default in LineageOS, CalyxOS and crDroid
    • You would rather never think about it
  • Pick Fossify Calendar

    If it has to stand alone

    • You want no account and no sync adapter
    • Your phone is on Android 8 or 9
    • You already run the Fossify suite
    • You want the largest feature set
  • Pick Calendula

    If it should look current

    • You want Material 3 Expressive throughout
    • Your phone is on Android 10 or newer
    • You prefer MIT to GPL
    • You can live with the newest of the three

What all three share

The permission one is what surprises people. I checked all three manifests and the INTERNET count is zero in each, so "your data never leaves the device" is not a Calendula feature. In this corner of the ecosystem it is table stakes, and anyone selling it to you as a differentiator — me included, if I ever do — is overselling.

They all read Android's system calendar, so a CalDAV account synced by DAVx⁵ shows up in every one of them and none of them locks you in. Setting that up is covered in the Nextcloud on Android guide.

Side by side

CalendulaEtarFossify Calendar
LicenceMITGPLv3GPLv3
Minimum Android106.08.0
Where your events liveSystem calendar onlySystem calendar onlyOwn database, CalDAV mirrored into it
Interface built withJetpack Compose, Material 3 ExpressiveAndroid Views, AOSP-derivedAndroid Views
INTERNET permissionNoneNoneNone
Started life asWritten from scratchA fork of AOSP CalendarA fork of Simple Calendar
Version checked2.20.31.0.571.10.3

The one difference that changes anything

Strip away the styling and there is a single architectural split, and it is not the one the app listings would suggest.

Calendula and Etar are pure front-ends. Neither has a database. They read and write Android's CalendarContract directly, and that is the whole storage story — Etar's source tree has no database layer in 2,211 files, and neither does mine. Whatever sync adapter put a calendar on your device owns the data; we just draw it.

Fossify Calendar keeps its own store. It has a Room database, and for CalDAV calendars you switch on in its settings it mirrors the system provider's events into that database, matched by import ID. Your events then exist in two places, and the copy has to be reconciled. Worth stating because fossify.org describes the app as using the system calendar "rather than maintaining a separate database"; the source says otherwise, and the source is what I went by.

Neither model is the correct one. What each one buys:

The detail behind each verdict

Etar

It is mostly Java and built on Views rather than Compose, which is exactly why it is stable: that code has been fixed for a long time, on more real devices than anything I will write this decade. If you want a calendar you never have to think about, Etar is the honest recommendation.

Fossify Calendar

The feature surface is what a decade of accumulated Simple Calendar history buys you, and the separate store is what lets it offer things the provider's schema has no column for.

Corrected 20 September 2026. This paragraph used to say the separate store made Fossify the only one of the three usable on a phone with no calendar account at all. That was wrong when I wrote it, and not in one way but two. Calendula has created device-only local calendars since 2.2.0 in June 2026 — Settings → Calendars → Add calendar — three months before I published the claim. And Etar offers an offline calendar of its own, which I never checked. The superlative was the error: I had a reason to believe it of Fossify and no evidence at all about the other two.

Calendula

The design is the reason: Compose on Material 3 Expressive throughout — the shapes, the spring-based motion between views, the type scale, dynamic colour from your wallpaper. Etar and Fossify are Views-based apps with Material touches. That is the only difference I would argue hard for. Secondary, and genuinely secondary: it is MIT rather than GPL.

The counterweight: version 0.1.0 shipped in June 2026, three months before this page, while Etar has been in production for years. If "battle-tested" is what you are shopping for, I am not it yet, and you should take that seriously rather than take my word that it is fine.

A note on Simple Calendar

You will still find Simple Calendar recommended in older threads. Simple Mobile Tools, the suite it belonged to, was sold to the app publisher ZipoApps in December 2023, and the published builds afterwards carried advertising. Fossify is the community fork, started by a contributor to the original project, and it is where that lineage is now maintained. If a list from 2022 sent you to Simple Calendar, Fossify Calendar is what it meant.

How this was checked

Verified on , against the versions in the table:

If something here is wrong or has gone stale, email me at support@jeanlucmakiola.de and I will fix it. Getting a competitor's facts wrong is worse for me than losing the comparison.

Back to Calendula — or the F-Droid listing if you have decided.