RainLoop vs WildDuck
A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | RainLoop | WildDuck |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 15 · At risk | 86 · Excellent |
| Status | Archived | Actively maintained |
| Category | Mail Servers | Mail Servers |
| License | AGPL-3.0 | EUPL-1.2 |
| Language | PHP | JavaScript |
| Setup difficulty | Easy | Hard |
| Min. RAM | 128 MB | 1,024 MB |
| Deployment | docker, bare-metal, source | docker, bare-metal |
| GitHub stars | ★ 4,114 | ★ 2,108 |
| First released | 2013 | 2017 |
| Replaces | Gmail, Outlook Web | Microsoft Exchange, Gmail |
What are RainLoop and WildDuck?
RainLoop
RainLoop is a fast, simple webmail client with a modern interface that works with any IMAP and SMTP server. It stores no email data itself, acting as a thin client.
- Modern, responsive UI
- No database required
- Multi-account support
- Works with any IMAP server
WildDuck
WildDuck is a modern, scalable mail server providing IMAP, POP3, and a full REST API for managing mailboxes. It stores messages in MongoDB and is designed for clustered, highly available deployments.
- IMAP and POP3
- Full REST API
- MongoDB storage
- Designed for scale
RainLoop vs WildDuck: key differences
The biggest difference is maintenance: RainLoop's repository is archived and no longer developed, while WildDuck is actively maintained. RainLoop is written in PHP, while WildDuck is built with JavaScript. Licensing differs — AGPL-3.0 for RainLoop versus EUPL-1.2 for WildDuck. RainLoop is the lighter option, starting around 128 MB of RAM against 1,024 MB for WildDuck. RainLoop is the more established project (first released 2013), while WildDuck arrived in 2017.
Why pick each one
Choose RainLoop if…
- Released under the AGPL-3.0 license
- Easy to set up — beginner-friendly
- First-class Docker support for quick deployment
- Active community (4.1k GitHub stars)
Watch out for
- Development largely stalled
- SnappyMail is the active fork
Choose WildDuck if…
- API-driven management
- Horizontally scalable
Watch out for
- Requires MongoDB
- Complex to operate
Frequently asked questions
Is RainLoop or WildDuck better?
RainLoop is the stronger all-round pick: it has both the larger community and the simpler easy setup. Consider RainLoop if its specific feature set fits your needs better.
Are RainLoop and WildDuck free and open-source?
Yes. RainLoop is licensed under AGPL-3.0 and WildDuck under EUPL-1.2. Both can be self-hosted at no software cost.
Can I run RainLoop and WildDuck with Docker?
RainLoop: yes. WildDuck: yes.
Which is lighter on resources, RainLoop or WildDuck?
RainLoop has the smaller minimum footprint at 128 MB of RAM, compared to about 1,024 MB for WildDuck. Real-world usage depends on library size, user count, and enabled features.