Etar vs Horde Kronolith
A side-by-side comparison of two self-hosted calendar & contacts options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | Etar | Horde Kronolith |
|---|---|---|
| Deploy effort | Read-the-docs project | Read-the-docs project |
| Health score | 87 · Excellent | 69 · Good |
| Category | Calendar & Contacts | Calendar & Contacts |
| License | GPL-3.0 | GPL-2.0 |
| Language | Java | PHP |
| Setup difficulty | Medium | Hard |
| Min. RAM | 256 MB | 256 MB |
| Deployment | source | bare-metal |
| GitHub stars | ★ 2,603 | ★ 10 |
| First released | 2016 | 2003 |
| Replaces | Google Calendar | Google Calendar, Exchange |
What are Etar and Horde Kronolith?
Etar
Etar is an open-source Android calendar app forked from AOSP Calendar. It has no server of its own: pair it with DAVx5 and any self-hosted CalDAV server such as Radicale, Baikal or Nextcloud to keep events under your control.
- CalDAV support
- Event API
- Mobile sync friendly
- Open data formats
Horde Kronolith
Kronolith is the calendar component of the Horde groupware framework. It provides shared calendars, event management, and supports CalDAV synchronization with desktop and mobile clients.
- Part of Horde groupware
- Shared calendar support
- CalDAV synchronization
Etar vs Horde Kronolith: key differences
Etar is written in Java, while Horde Kronolith is built with PHP. Licensing differs — GPL-3.0 for Etar versus GPL-2.0 for Horde Kronolith. Horde Kronolith is the more established project (first released 2003), while Etar arrived in 2016. Etar has the considerably larger community, at 2,603 GitHub stars versus 10.
Why pick each one
Choose Etar if…
- Open ecosystem
- No vendor lock-in
Watch out for
- Mainly a client project
- Server piece is minimal
Choose Horde Kronolith if…
- Released under the GPL-2.0 license
- Written in PHP
- Tiny footprint — runs in 256 MB RAM
Frequently asked questions
Is Etar or Horde Kronolith better?
Etar is the stronger all-round pick: it has both the larger community and the simpler medium setup. Consider Horde Kronolith if its specific feature set fits your needs better.
Are Etar and Horde Kronolith free and open-source?
Yes. Etar is licensed under GPL-3.0 and Horde Kronolith under GPL-2.0. Both can be self-hosted at no software cost.
Can I run Etar and Horde Kronolith with Docker?
Etar: check the project docs for container support. Horde Kronolith: check the project docs for container support.