MailHog vs smtp4dev
A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | MailHog | smtp4dev |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 26 · At risk | 85 · Excellent |
| Category | Mail Servers | Mail Servers |
| License | MIT | GPL-3.0 |
| Language | Go | C# |
| Setup difficulty | Easy | Easy |
| Min. RAM | 64 MB | 128 MB |
| Deployment | docker, binary, source | docker, binary |
| GitHub stars | ★ 16,167 | ★ 3,979 |
| First released | 2014 | 2015 |
| Replaces | Mailtrap | Mailtrap |
What are MailHog and smtp4dev?
MailHog
MailHog is an email testing tool that provides a fake SMTP server for developers, capturing messages and presenting them in a web UI. It includes an API and chaos-testing features.
- Fake SMTP for testing
- Web UI and JSON API
- Chaos monkey testing
- Single Go binary
smtp4dev
smtp4dev is a dummy SMTP server that catches messages sent by applications and shows them in a web interface. It lets developers test email functionality without sending real mail.
- Catches outgoing email
- Web inbox viewer
- IMAP access
- API for automation
MailHog vs smtp4dev: key differences
MailHog is written in Go, while smtp4dev is built with C#. Licensing differs — MIT for MailHog versus GPL-3.0 for smtp4dev. MailHog is the lighter option, starting around 64 MB of RAM against 128 MB for smtp4dev. MailHog has the considerably larger community, at 16,167 GitHub stars versus 3,979.
Why pick each one
Choose MailHog if…
- Zero-config SMTP capture
- Handy web viewer
- Built-in chaos testing
Watch out for
- Development largely stalled
- Development use only
Choose smtp4dev if…
- Easy local testing
- Cross-platform
Watch out for
- Not for real delivery
- Development use only
Frequently asked questions
Is MailHog or smtp4dev better?
Neither is universally better. MailHog has the larger community; both share a easy setup difficulty, so the decision comes down to features and licensing.
Are MailHog and smtp4dev free and open-source?
Yes. MailHog is licensed under MIT and smtp4dev under GPL-3.0. Both can be self-hosted at no software cost.
Can I run MailHog and smtp4dev with Docker?
MailHog: yes. smtp4dev: yes.
Which is lighter on resources, MailHog or smtp4dev?
MailHog has the smaller minimum footprint at 64 MB of RAM, compared to about 128 MB for smtp4dev. Real-world usage depends on library size, user count, and enabled features.