The relationship
MailHog OSS (github.com/mailhog/MailHog) is a popular open-source, self-hosted SMTP testing tool written in Go by Ian Kent. MailHog.site is a separate hosted SaaS platform built from scratch. Different codebase, different team, similar mission.
Feature comparison
| Feature | MailHog.site | MailHog OSS |
|---|---|---|
| Hosting | Hosted SaaS | Self-hosted |
| Setup time | 60 seconds | 10–30 minutes |
| SMTP capture | ✅ | ✅ |
| Real-time updates | ✅ SSE | ✅ WebSocket |
| Spam scoring | ✅ rspamd engine | ❌ |
| HTML compatibility | ✅ 12+ clients | ❌ |
| REST API | ✅ Full CRUD | ✅ Basic |
| Team access | ✅ Multi-user | ❌ Single-user |
| Per-inbox auth | ✅ argon2id | ❌ No auth |
| Retention & cleanup | ✅ Automatic | Manual |
| Search & filtering | ✅ Full-text | ✅ Basic |
| Attachments | ✅ | ✅ |
| Cost | Free – $29/mo | Free (self-host) |
| Maintenance | Zero | You maintain it |
When MailHog OSS is the right choice
- You're a solo developer who wants a local-only SMTP capture tool
- You're comfortable running Docker or Go binaries on your machine
- You don't need spam scoring, HTML checks, or team features
- Data sensitivity requires all emails to stay on your local machine
- Budget is zero and you're willing to handle maintenance
When MailHog.site is the right choice
- You want to start testing in 60 seconds without installing anything
- Your team needs shared inboxes with access control
- You need spam scoring to catch deliverability issues early
- You need HTML compatibility checks across email clients
- You want a REST API for CI/CD integration testing
- You don't want to maintain infrastructure for a dev tool
Migration from MailHog OSS
If you're currently using MailHog OSS and want to upgrade to MailHog.site, the migration is straightforward: sign up, create an inbox, and update your SMTP configuration (host, port, username, password) in your app's environment variables. The SMTP protocol is standard — any app that works with MailHog OSS will work with MailHog.site.
Upgrade from self-hosted
Get spam scoring, HTML checks, and team features — no Docker required.
Start free →