MailCatcher
Tiny Ruby-based local SMTP catcher.
MailCatcher is a Ruby gem that runs a local SMTP server on port 1025 and a web UI on 1080. It is common in Rails projects and shows the HTML, plain-text, and raw-source version of each captured message. Development is slow, so Mailpit is usually the stronger default today.
At an early stage the deciding factors are what the free tier actually covers, what the first paid invoice looks like, and how much of a founding engineer's week the setup costs. Feature depth that only matters at a million sends a month is noise until it is not.
Against a waitlist, a launch announcement, onboarding email, and the first transactional sends, MailCatcher covers developer experience, and does not cover scheduling, SDK breadth, and webhook coverage. Whether that gap matters depends on how central those are to the build.
- Free tier: Free, MIT-licensed
- Best published rate per 1,000: Tiers not published in comparable form
- Starts at: Free
- DX score: 6/10
- Deliverability: Not applicable.
- Operating since: Not published
- Scheduling: No
- SDKs: None
- Webhooks: No
Not applicable.
Rails teams already running it in development.
Non-Ruby projects, which get a lighter setup from Mailpit.
- › Installs as a Ruby gem, familiar in Rails stacks
- › SMTP on 1025 with a web UI and JSON API on 1080
- › Shows HTML, plain text, and raw source per message
- › Release cadence is slow with little active feature work
- › Needs a Ruby runtime where Mailpit ships a static binary
- › HTML rendering trails newer catchers
Features at a glance
| API | Yes |
| SMTP | Yes |
| SDKs | None |
| Webhooks | No |
| Templates | none |
| React Email | No |
| Batch send | No |
| Scheduled send | No |
| Suppressions | No |
| Multi-tenant | No |
| Inbound parsing | No |
| Event stream | No |
| Idempotency keys | No |
| Dedicated IP | No |