Plunk

Open-source email platform for sending transactional and marketing emails, self-hostable with a clean API.

Open source alternative to:

Mailchimp

Sendgrid

Kit

Plunk is an open-source email platform built for developers who want full control over their email infrastructure. It supports transactional emails, broadcasts, and contact management — all in one place with a clean REST API.

Designed as a self-hosted alternative to services like Mailchimp and SendGrid, Plunk lets you manage contacts, segment audiences, and send campaigns from your own infrastructure. It features event tracking, automation triggers, and a simple dashboard for monitoring delivery metrics.

Built with TypeScript and deployable via Docker, Plunk is easy to run on your own server. It connects to any SMTP provider (AWS SES, Postmark, etc.) for actual email delivery, giving you the flexibility to keep costs low while retaining full ownership of your data.