Calendar
Open alternatives4

A calendar app that runs on a Nextcloud server, letting you sync events from your devices and edit them in a web browser. It is for people and teams who want to keep their calendar on their own Nextcloud server.
Has 3 of 6 · Phone app ✗ +1
How many people bookmarked its code on GitHub. It shows how popular it is, not how good it is or how well it replaces the app.
How hard it is to start using it. Easy: install it like a normal app, or use it in your browser. Advanced: you run it on your own server, use the command line, or it is a tool for developers.
Its code changed within the last year, so someone is still looking after it.
Does the whole job.
Ordered by how fully it replaces the app, Verified, setup and, when there are enough, people's votes.

Thunderbird is a free, open-source email app for Windows, macOS and Linux that also includes calendars and contacts, with an Android app for email. It suits people who want to manage their email and calendars in one desktop program without relying on a big tech company.
Has 2 of 6
How many people bookmarked its code on GitHub. It shows how popular it is, not how good it is or how well it replaces the app.
How hard it is to start using it. Easy: install it like a normal app, or use it in your browser. Advanced: you run it on your own server, use the command line, or it is a tool for developers.
Its code changed within the last year, so someone is still looking after it.
r/TrueOpenSource mods checked it: an open-source license, still looked after, and it really does the job.
Does part of the job.
Ordered by how fully it replaces the app, Verified, setup and, when there are enough, people's votes.

Fossify Calendar is a calendar app for Android phones that lets you plan events, reminders and repeating appointments. It is aimed at people who want a private calendar with no ads or tracking.
Has 2 of 6
Continues Simple Calendar after the original was discontinued
How many people bookmarked its code on GitHub. It shows how popular it is, not how good it is or how well it replaces the app.
How hard it is to start using it. Easy: install it like a normal app, or use it in your browser. Advanced: you run it on your own server, use the command line, or it is a tool for developers.
Its code changed within the last year, so someone is still looking after it.
Does part of the job.
Ordered by how fully it replaces the app, Verified, setup and, when there are enough, people's votes.
- Simple CalendarNot on this map
- Fossify CalendarCarries it on

Etar is a calendar app for Android phones that shows month, week, day and agenda views. It is for people who want a simple calendar that can keep events on the phone or sync them with a calendar server.
Has 1 of 6
How many people bookmarked its code on GitHub. It shows how popular it is, not how good it is or how well it replaces the app.
How hard it is to start using it. Easy: install it like a normal app, or use it in your browser. Advanced: you run it on your own server, use the command line, or it is a tool for developers.
Its code changed within the last year, so someone is still looking after it.
Does part of the job.
Ordered by how fully it replaces the app, Verified, setup and, when there are enough, people's votes.
YesPartlyNoNot checked yet