MailDev
MailDev is a free, local SMTP server and web inbox for developers checking email generated by applications during development.
What MailDev is
MailDev is a free, local SMTP server and web inbox for developers checking email generated by applications during development. It listens for SMTP mail on port 1025 and provides a REST API under `/api` for listing, reading, searching, downloading, and deleting messages. The inbox shows rendered HTML, plain text, headers, and raw email source, while a responsive preview helps inspect rendering at different viewport widths. New messages arrive through WebSockets without refreshing or polling. Any language that speaks SMTP can connect, with setup examples for Nodemailer, Django, Ruby on Rails, Laravel, and Spring Boot. An optional MCP server allows compatible AI clients to search and read the development inbox and check delivery. MailDev can selectively relay mail through an outgoing SMTP server, including optional auto-relay rules. It runs locally through npx, a global npm install, or Docker. Mail is unencrypted, unauthenticated by default, and retained without a limit unless `--max-emails` is configured.
Good
- Free and open source under the MIT license
- Displays HTML, text, headers, and raw source
- REST API supports mail management actions
- Live inbox updates use WebSockets
- Works with any SMTP-speaking language
Watch out
- No authentication by default
- Stores email unencrypted
- Not intended for public or production traffic
- Unlimited retention unless manually capped
Who it suits
It suits developers testing email produced by their projects with a local inbox. It is also useful for teams using SMTP-based applications or compatible AI clients.
Verdict
MailDev provides a focused local mailbox for inspecting development email, with API access, live updates, and broad SMTP compatibility. Its default security settings require careful isolation from public or production traffic.
Plans and prices
From MailDev's own pricing page, checked 5 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| MailDev | Free | Free and open source · MIT licensed · Runs locally |
The facts
Each one read from MailDev's own pages, with the date it was checked.
What it does
- AI integration
- MailDev includes an optional MCP server that lets compatible AI clients search and read the development inbox and check email delivery.checked 5 Oct 2026
- Audience
- The maker describes MailDev as a development tool for developers testing email generated by their projects.checked 5 Oct 2026
- Email formats
- The inbox displays rendered HTML, plain text, headers, and raw email source.checked 5 Oct 2026
- Email retention
- MailDev keeps emails without a configured limit by default; its `--max-emails` option can cap the inbox and discard older messages.checked 5 Oct 2026
- Framework integrations
- The docs provide setup examples for Nodemailer, Django, Ruby on Rails, Laravel, and Spring Boot, and say any language that speaks SMTP can connect.checked 5 Oct 2026
- Install options
- The maker documents running MailDev with npx, a global npm install, or Docker.checked 5 Oct 2026
- Live updates
- New messages appear in the inbox over WebSockets without a refresh or polling.checked 5 Oct 2026
- Preview
- The web interface offers a responsive preview for checking how email renders at different viewport widths.checked 5 Oct 2026
- Purpose
- MailDev is a local SMTP server and web inbox for developers to catch and inspect email sent by an app during development.checked 5 Oct 2026
- Relay
- MailDev can selectively relay messages through a configured outgoing SMTP server, with optional auto-relay rules.checked 5 Oct 2026
- Security
- MailDev accepts mail from anyone, stores it unencrypted, and has no authentication by default, so the docs warn against exposing it to the public internet or using it for production traffic.checked 5 Oct 2026
- SMTP and API
- MailDev listens for SMTP on port 1025 and provides a REST API under `/api` for listing, reading, searching, downloading, and deleting mail.checked 5 Oct 2026
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