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Horde Kronolith vs Decsync Calendar Sync

A side-by-side comparison of two self-hosted calendar & contacts options — licensing, setup difficulty, resource needs, and what each one replaces.

Not the right match-up?
HO Horde Kronolith Calendar application from the Horde groupware suite VS DE Decsync Calendar Sync File-based calendar and contacts synchronization
FeatureHorde KronolithDecsync Calendar Sync
Deploy effortRead-the-docs projectRead-the-docs project
Health score69 · Good15 · At risk
CategoryCalendar & ContactsCalendar & Contacts
LicenseGPL-2.0GPL-3.0
LanguagePHPKotlin
Setup difficultyHardMedium
Min. RAM256 MB128 MB
Deploymentbare-metalsource, binary
GitHub stars★ 10★ 699
First released20032018
ReplacesGoogle Calendar, ExchangeGoogle Calendar

What are Horde Kronolith and Decsync Calendar Sync?

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

Decsync Calendar Sync

Decsync is a method and toolset for synchronizing calendars and contacts via a shared folder rather than a central server. Self-hosters pair it with a file-sync service to keep events consistent across devices.

  • Folder-based sync
  • No central server
  • Calendar and contacts
  • Pairs with any file sync

Horde Kronolith vs Decsync Calendar Sync: key differences

Horde Kronolith is written in PHP, while Decsync Calendar Sync is built with Kotlin. Licensing differs — GPL-2.0 for Horde Kronolith versus GPL-3.0 for Decsync Calendar Sync. Decsync Calendar Sync is the lighter option, starting around 128 MB of RAM against 256 MB for Horde Kronolith. Horde Kronolith is the more established project (first released 2003), while Decsync Calendar Sync arrived in 2018. Decsync Calendar Sync has the considerably larger community, at 699 GitHub stars versus 10.

Why pick each one

Choose Horde Kronolith if…

  • Released under the GPL-2.0 license
  • Written in PHP
  • Tiny footprint — runs in 256 MB RAM
Horde Kronolith details

Choose Decsync Calendar Sync if…

  • Server-free architecture
  • Privacy friendly

Watch out for

  • Requires a sync layer
  • Setup is non-trivial
Decsync Calendar Sync details

Frequently asked questions

Is Horde Kronolith or Decsync Calendar Sync better?

Decsync Calendar Sync 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 Horde Kronolith and Decsync Calendar Sync free and open-source?

Yes. Horde Kronolith is licensed under GPL-2.0 and Decsync Calendar Sync under GPL-3.0. Both can be self-hosted at no software cost.

Can I run Horde Kronolith and Decsync Calendar Sync with Docker?

Horde Kronolith: check the project docs for container support. Decsync Calendar Sync: check the project docs for container support.

Which is lighter on resources, Horde Kronolith or Decsync Calendar Sync?

Decsync Calendar Sync has the smaller minimum footprint at 128 MB of RAM, compared to about 256 MB for Horde Kronolith. Real-world usage depends on library size, user count, and enabled features.

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