The Best Free Open-Source Calendar Apps for Android

 Google apps are great, but they can be replaced. And sometimes (who said “Huawei”?) they have to be replaced by third-party apps that at least keep up to the standards set. Here is a brief review of the three calendar apps for Android that we found worthy.

The requirements for this list were simple but strong; that’s why, say, Microsoft Outlook or ZenDay are left outside. First of all, our apps should be free. Second, they should be open-source. Both requirements are equally important.

It’s clear why we’d rather have free apps. But why open-source? The reason is that the openness of the code inspires competent users to check these apps for malware elements, like viruses, backdoors, spy modules, and so on. Unlike proprietary apps that are hard to disassemble and look at what’s inside, these are quite transparent, so you can be sure they don’t spy or share your data. Well, there is a chance that some developer will insolently insert a piece of malware into an open-source app, but it’s suicidal behavior.

So, let’s take a look at the three free calendar apps for Android that are open-source and functional enough for everyday use.

Simple Calendar

Simple Calendar

When you see such a name, you may think there is nothing about it that the default one doesn’t offer (except for being unGoogle). It’s a part of Simple Mobile Tools suite, a series started by Slovakian developer Tibor Kaputa. The task of it is highly ambitious: can one man create or at least initiate a suite of apps that can take the place of analogs by Microsoft, Google, Apple, and other titans?

As for the calendar, the attempt is successful. It has most of the things we require from a calendar app. Along with plain calendar view, Simple Calendar has notifications, built-in search across records and events, multiple calendars, .ICS import and export, and so on.

Well, if you still want to use Google services for cloud syncing, Simple Calendar can do this. Due to the full support of CalDAV, it can sync with NextCloud, Google, Microsoft, Yahoo, and other cloud services.

And it is not ad-supported – a great step for free apps. Well, maintaining such apps for free is too much, even for a big enthusiast. So now, the free version is updated no more (though still functional). The paid version (yet still open-source) is available for $1.19, and for some European countries, it’s even cheaper. It’s just a step of support towards the developer, and it’s worth a coffee cup.


Etar screen

It’s, in fact, a take in AOSP Calendar, remixed by Suhail Alkowaileet and Jochen Sprickerhof. Not as functional as the previous app, it’s still a good option if you want it lightweight, free, and nice. Along with the cute design, it features notifications, various views, light and dark themes built-in, and so on.
Yes, it also supports CalDAV, like a decent Android app should. So it’s compatible with cloud calendar services as well. Local .ICS files can also be exported or imported. If you’re not ready to go local completely, it’s the salvation.
What the app lacks includes widgets (that’s terrible) and ads (that’s great).



If you want to use cloud synchronization with any of the previous two, but don’t trust Google with your private data (or can’t use services), DAVx⁵ is the way out. It dubs the functionality of the built-in Android’s DAV, so it can connect apps like Etar or Simple Calendar to cloud servers.

The greatness of DAVx⁵ is its independence of Google Services. So if you have removed them intendedly, or just bought a phone that goes without Google Services (say, one of the latest Huawei devices), DAVx⁵ will do the work and connect your calendar app to Google, iCloud, Yahoo, and other popular services. Self-hosting options, like Nextcloud or OwnCloud, are supported too.

Being an open-source one, DAVx⁵ is $4.69 on Google Play Store, and that’s a paradox. You may need such an app if you have a Google-free Android, but on such a device, you cannot access Play Store. There are longer ways, still, so if you want to reward the developers, you can buy the app officially and then get the APK somewhere else. Anyway, you’ll have to get this app working on these devices. Luckily, the developer offers a detailed guide.

What’s Your App?

If you are interested in free and open-source calendars, you may have some experience in handling them. Maybe you have something else to tell about these apps or want to bring in some other ones we missed. Drop a comment to share it!