Side by side
Merkuro Calendar (formerly Kalendar) vs Proton Calendar
Both stand on calendar apps. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Free plan LinuxWindows
Merkuro Calendar combines multi-source calendars with structured task management in a free KDE application. Stable packages are available through listed Linux channels, while Windows nightly builds are intended for testing.
Visit Merkuro Calendar (formerly Kalendar)
Free plan AndroidiPhone
Proton Calendar combines event management, scheduling features, and encrypted event details. The free plan has a 3-calendar limit; paid Proton Mail plans allow up to 25 calendars and add sharing and import/export features.
Visit Proton CalendarThe facts
| Merkuro Calendar (formerly Kalendar) | Proton Calendar | |
|---|---|---|
| Free plan | Yes | Yes |
| Open source | Not published | Not published |
| Runs on | Linux, Windows | Android, iPhone |
| Lowest paid plan | Free or on request | Free or on request |
| Plans published | 1 | 4 |
| Maker | Not published | Proton Calendar |
| Website | apps.kde.org | proton.me |
| On calendar apps | #85 of 198 | #31 of 198 |
Merkuro Calendar (formerly Kalendar): what it does well
- Supports Nextcloud, Google Calendar, Outlook, and CalDAV
- Month, week, and schedule event views
- Tasks include subtasks, tree view, and filters
- GPL-3.0-or-later licensed free software
- Linux and Windows availability
What to know first
- Nightly installers are labeled unstable
- Third-party distributors may alter privacy behavior
- No free trial is offered because it is free software
Proton Calendar: what it does well
- Event details are protected with end-to-end or zero-knowledge encryption.
- Free accounts include up to 3 calendars.
- Scheduling links and video meeting support are listed.
- Events can be added directly from Proton Mail.
- Notifications are available on mobile devices and desktop browsers.
What to know first
- The free plan is limited to 3 calendars.
- Calendar sharing and import/export are listed for paid plans.
- Only Android and iOS platforms are listed.
- Subscriptions purchased through proton.me renew automatically.
Alternatives to Merkuro Calendar (formerly Kalendar) Alternatives to Proton Calendar The whole list