Citadel vs Nextcloud Groupware
A side-by-side comparison of two self-hosted groupware options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | Citadel | Nextcloud Groupware |
|---|---|---|
| Deploy effort | Read-the-docs project | Under-an-hour setup |
| Category | Groupware | Groupware |
| License | GPL-3.0 | AGPL-3.0 |
| Language | C | JavaScript |
| Setup difficulty | Medium | Medium |
| Min. RAM | 512 MB | 1,024 MB |
| Deployment | bare-metal, source | docker, bare-metal, source |
| GitHub stars | ★ 100 | ★ 1,188 |
| First released | 1987 | 2016 |
| Replaces | Microsoft Exchange, Microsoft 365 | Microsoft 365, Google Workspace |
What are Citadel and Nextcloud Groupware?
Citadel
Citadel is a mature, all-in-one collaboration suite that integrates email, calendaring, address books, instant messaging, and bulletin boards. It is designed for easy installation and minimal maintenance.
- Integrated mail and calendar
- Built-in groupware web client
- Instant messaging and forums
- Easy installer
Nextcloud Groupware
Nextcloud Groupware bundles the Mail, Calendar, Contacts, and Deck apps to turn a Nextcloud instance into a full collaboration suite. It provides CalDAV and CardDAV synchronization for all clients.
- Integrated mail, calendar and contacts
- CalDAV and CardDAV sync
- Deck kanban boards
- Runs on existing Nextcloud
Citadel vs Nextcloud Groupware: key differences
Citadel is written in C, while Nextcloud Groupware is built with JavaScript. Licensing differs — GPL-3.0 for Citadel versus AGPL-3.0 for Nextcloud Groupware. Citadel is the lighter option, starting around 512 MB of RAM against 1,024 MB for Nextcloud Groupware. Citadel is the more established project (first released 1987), while Nextcloud Groupware arrived in 2016. Nextcloud Groupware has the considerably larger community, at 1,188 GitHub stars versus 100. Nextcloud Groupware lists first-class Docker deployment; Citadel does not.
Why pick each one
Choose Citadel if…
- Single-package setup
- Low resource needs
Watch out for
- Niche project
- Old-fashioned UI
Choose Nextcloud Groupware if…
- Tight Nextcloud integration
- Standards-based sync
Watch out for
- Requires Nextcloud
- Mail app needs external IMAP
Frequently asked questions
Is Citadel or Nextcloud Groupware better?
Neither is universally better. Nextcloud Groupware has the larger community; both share a medium setup difficulty, so the decision comes down to features and licensing.
Are Citadel and Nextcloud Groupware free and open-source?
Yes. Citadel is licensed under GPL-3.0 and Nextcloud Groupware under AGPL-3.0. Both can be self-hosted at no software cost.
Can I run Citadel and Nextcloud Groupware with Docker?
Citadel: check the project docs for container support. Nextcloud Groupware: yes.
Which is lighter on resources, Citadel or Nextcloud Groupware?
Citadel has the smaller minimum footprint at 512 MB of RAM, compared to about 1,024 MB for Nextcloud Groupware. Real-world usage depends on library size, user count, and enabled features.