What is MailHog?
MailHog intercepts and stores SMTP messages during development, providing a web UI and JSON API for viewing and managing test emails, with the option to forward messages to real mail servers.
What MailHog does
The capabilities that matter for email testing dev, normalised so it lines up with every alternative. “-” means we haven't confirmed it, not that it's missing.
- API assertions
- ✓
- Rendering preview
- ✓
- Spam score check
- ✗
- Blocklist deliverability check
- ✗
- SMS testing
- ✗
- Production sending addon
- ✓
- Ci cd integration
- ✗
- Multi user inboxes
- ✓
- Open source
- ✓
Platform & deployment
Independently observed- macOS
- Web
- Linux
- Cloud / SaaS
- Self-hosted
Security & compliance
Known vulnerabilities: 0 (0 in the last 12 months) sourcea count reflects scale & disclosure, not quality
MailHog alternatives
Other email testing dev we track, ranked by the same independent score.
- Testmail.appProgrammable email testing service for developers and QA automating end-to-end test verificationlow · 42%
- Maildevlow · 24%
- MailosaurPlatform for testing email and SMS communications end-to-end before productionmedium · 55%
- Email on AcidEmail testing and validation platform for pre-send campaign quality assurancemedium · 66%
- GreenMaillow · 31%
- MailSlurpOn-demand email and SMS testing platform for developersmedium · 54%
Compare MailHog
Side by side against other email testing dev, attribute by attribute, with a source on every value.
The Vioscale score: one lens on the evidence
Not user reviews and not a paid placement: a confidence-weighted blend of the independent signals below (adoption, activity, security posture, and more), which you can sort and re-weight yourself. Vendors can correct their listing but can never move their rank, and stars are weighted low as a vanity metric. It is one way to read the evidence for MailHog, not the verdict.
| Signal | Score | Weight | Contribution | Evidence |
|---|---|---|---|---|
| Capabilities | 75 | 0.08 | 6.3 | ✓ |
| Release cadence | 94 | 0.05 | 4.9 | ✓ |
| Stars | 79 | 0.03 | 2.1 | ✓ |
| Dependent projects | 18 | 0.06 | 1.1 | ✓ |
| Security score | 26 | 0.04 | 1.1 | ✓ |
| Price level | 0 | 0.05 | 0.0 | - |
| Reliability | 0 | 0.07 | 0.0 | - |
| Integrations | 0 | 0.09 | 0.0 | - |
| Development activity | 0 | 0.09 | 0.0 | ✓ |
| Security posture | 0 | 0.07 | 0.0 | - |
| Package downloads | 0 | 0.14 | 0.0 | - |
| Pricing transparency | 0 | 0.08 | 0.0 | - |
| Developer Q&A activity | 0 | 0.06 | 0.0 | - |
Computed . Re-weight it by intent, or see the full method.
All data & sourcesshow ↓
Every value we hold, with its source, retrieval date, and confidence. This is the evidence behind the score: don't trust it, verify it.
Activity
| Attribute | Value | Evidence |
|---|---|---|
| Commits last 30d | 0 | mediumsource · 2026-08-18 · 65% |
Adoption
Features
| Attribute | Value | Evidence |
|---|---|---|
| Capabilities | Open source, Api assertions, Rendering preview, Multi user inboxes, Production sending addon | mediumsource · 2026-08-21 · 60% |
Language
| Attribute | Value | Evidence |
|---|---|---|
| Primary | Go | highsource · 2026-08-26 · 90% |
License
| Attribute | Value | Evidence |
|---|---|---|
| Spdx | MIT | highsource · 2026-08-26 · 95% |
Pricing
| Attribute | Value | Evidence |
|---|---|---|
| Model | commercial | lowsource · 2026-08-26 · 40% |