Side by side
Mailtrap Email Sandbox vs smtp4dev
Both stand on email testing software. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Free plan APIWeb
Mailtrap Email Sandbox focuses on inspecting and testing messages before delivery, with API automation and client previews. Check the plan limits and remember it does not send email to real recipients.
Visit Mailtrap Email Sandbox Free plan APILinuxMac+3
smtp4dev provides a local testing environment with message inspection, protocol access, and API support. When deploying with Docker, follow the localhost-binding guidance if external access is not needed.
Visit smtp4devThe facts
| Mailtrap Email Sandbox | smtp4dev | |
|---|---|---|
| Free plan | Yes | Yes |
| Open source | Not published | Not published |
| Runs on | API, Web | API, Linux, Mac, Self-hosted, Web, Windows |
| Lowest paid plan | Basic: $17 a month | Not published |
| Plans published | 5 | None |
| Maker | Not published | Not published |
| Website | mailtrap.io | github.com |
| On email testing software | #13 of 28 | #17 of 28 |
Mailtrap Email Sandbox: what it does well
- Inspects content, source, headers, and spam scores
- Supports automated testing through its API
- Offers previews across named email clients
- Works with SMTP-compatible apps and frameworks
- Free plan includes 50 test emails monthly
What to know first
- Free plan has one sandbox
- Free plan allows 50 test emails monthly
- Not designed to deliver email to real addresses
- Basic plan has no chat support
smtp4dev: what it does well
- Free to use, with no trial requirement listed.
- Supports SMTP, IMAP, and POP3.
- Offers HTML rendering and compatibility reports.
- API supports automated tests and external applications.
- Multiple installation options include Docker and winget.
What to know first
- Published Docker ports may expose captured emails externally.
- Windows winget requires Windows 10 version 1809 or newer.
- TLS certificates are self-signed when generated automatically.
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