Citadel vs Horde Groupware
A side-by-side comparison of two self-hosted groupware options — licensing, setup difficulty, resource needs, and what each one replaces.
Not the right match-up?
Citadel
All-in-one groupware, mail and collaboration server
VS
Horde Groupware
PHP groupware suite with webmail and calendaring
| Feature | Citadel | Horde Groupware |
|---|---|---|
| Category | Groupware | Groupware |
| License | GPL-3.0 | GPL-2.0 |
| Language | C | PHP |
| Setup difficulty | Medium | Hard |
| Min. RAM | 512 MB | 512 MB |
| Deployment | bare-metal, source | bare-metal, source |
| GitHub stars | ★ 100 | ★ 243 |
| First released | 1987 | 2003 |
| Replaces | Microsoft Exchange, Microsoft 365 | Microsoft Exchange |
Why pick each one
Choose Horde Groupware if…
- Released under the GPL-2.0 license
- Written in PHP
- Lightweight — runs in 512 MB RAM
Frequently asked questions
Is Citadel or Horde Groupware better?
Neither is universally better. Horde Groupware has the larger community, while Citadel is simpler to set up (medium difficulty). Choose based on the comparison table above and your own setup.
Are Citadel and Horde Groupware free and open-source?
Yes. Citadel is licensed under GPL-3.0 and Horde Groupware under GPL-2.0. Both can be self-hosted at no software cost.
Can I run Citadel and Horde Groupware with Docker?
Citadel: check the project docs for container support. Horde Groupware: check the project docs for container support.