smtp4dev vs testmail.app
smtp4dev
github.comtestmail.app
testmail.appSide by side
| Figure | smtp4dev | testmail.app |
|---|---|---|
| Price from | — | $9/mo |
| Free plan | — | Yes |
| Free trial | — | Yes |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | — |
| API | Yes | Yes |
| Self-hosted | Yes | — |
| Plans published | 0 | 6 |
| Spec score · Email Testing Software | 7.2 (#23) | 8.3 (#9) |
| Purpose | smtp4dev is a fake SMTP server for development and testing, letting developers test email without sending it to real customers. | testmail.app receives, parses, spam-tests, and indexes test emails so they can be retrieved by API for automated end-to-end testing. |
| Testing integrations | The testing guide covers programmatic use with the REST API, SignalR email notifications, Testcontainers examples for multiple programming languages, and direct use of the SMTP server component in .NET. | Documentation includes examples for Cypress, Selenium and TestCafe using both JSON and GraphQL APIs. |
Plans
testmail.app
- FreeFree
- Essential$9 a month
- Pro$29 a month
- Enterprise$89 a month
- Unlimited$269 a month
- CustomPriced on request
In their own words
testmail.app
testmail.app receives, parses, spam-tests, and indexes test emails for automated end-to-end testing. Messages sent to addresses such as `{namespace}.{tag}@inbox.testmail.app` are routed into mailboxes, allowing tests to create addresses and mailboxes dynamically. The service provides simple JSON and GraphQL APIs, with client examples for JavaScript, PHP, Ruby, Python, Go, Bash, C#, and Java. Search includes wildcard queries, live waits for new mail, sorting, pagination, attachments, and SpamAssassin reports. GraphQL adds advanced filters, field selection, and custom sorting unavailable in the simple JSON API. Documented integrations cover Cypress, Selenium, TestCafe, and email OTP testing. New accounts receive a 14-day trial without a credit card, then move to the free plan. Free includes 100 emails monthly and one-day retention. Paid plans start at $9/mo (annual). Hosting uses AWS, with encrypted data and passwordless logins.