Cyrus IMAP vs Citadel
A side-by-side comparison of two self-hosted apps from related categories — licensing, setup difficulty, resource needs, and what each one replaces.
Not the right match-up?
Cyrus IMAP
Scalable IMAP and POP server for large deployments
VS
Citadel
All-in-one groupware, mail and collaboration server
| Feature | Cyrus IMAP | Citadel |
|---|---|---|
| Category | Mail Servers | Groupware |
| License | BSD-3-Clause | GPL-3.0 |
| Language | C | C |
| Setup difficulty | Hard | Medium |
| Min. RAM | 1,024 MB | 512 MB |
| Deployment | bare-metal, source | bare-metal, source |
| GitHub stars | ★ 641 | ★ 100 |
| First released | 1994 | 1987 |
| Replaces | Microsoft Exchange | Microsoft Exchange, Microsoft 365 |
Why pick each one
Frequently asked questions
Is Cyrus IMAP or Citadel better?
Neither is universally better. Cyrus IMAP 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 Cyrus IMAP and Citadel free and open-source?
Yes. Cyrus IMAP is licensed under BSD-3-Clause and Citadel under GPL-3.0. Both can be self-hosted at no software cost.
Can I run Cyrus IMAP and Citadel with Docker?
Cyrus IMAP: check the project docs for container support. Citadel: check the project docs for container support.