RainLoop vs MailCatcher
A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.
Not the right match-up?
RainLoop
Simple, modern and fast web-based email client
VS
MailCatcher
Catch-all SMTP server for inspecting test email
| Feature | RainLoop | MailCatcher |
|---|---|---|
| Category | Mail Servers | Mail Servers |
| License | AGPL-3.0 | MIT |
| Language | PHP | Ruby |
| Setup difficulty | Easy | Easy |
| Min. RAM | 128 MB | 128 MB |
| Deployment | docker, bare-metal, source | docker, binary, source |
| GitHub stars | ★ 4,120 | ★ 6,774 |
| First released | 2013 | 2010 |
| Replaces | Gmail, Outlook Web | Mailtrap |
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)
Choose MailCatcher if…
- Released under the MIT license
- Easy to set up — beginner-friendly
- First-class Docker support for quick deployment
- Mature project with 6.8k GitHub stars
Frequently asked questions
Is RainLoop or MailCatcher better?
Neither is universally better. MailCatcher has the larger community; both share a easy setup difficulty, so the decision comes down to features and licensing.
Are RainLoop and MailCatcher free and open-source?
Yes. RainLoop is licensed under AGPL-3.0 and MailCatcher under MIT. Both can be self-hosted at no software cost.
Can I run RainLoop and MailCatcher with Docker?
RainLoop: yes. MailCatcher: yes.