Plunk gives SaaS builders one open source home for product emails, newsletters and automated flows, and bills only for what they send

A typical SaaS ends up with one service for password resets and receipts, another for the newsletter and a third for onboarding drips, each holding its own copy of the customer list. Plunk folds all of that into one place. You send transactional email through its API, run campaigns with scheduling, build automated workflows in a visual editor, and segment your audience in real time, all against the same set of contacts.

Dries Augustyns started Plunk in late 2022 and launched it on Product Hunt in March 2023. Since then the project has gone open source under AGPL-3.0, and the GitHub repository has since passed five thousand stars. It has been described as a bootstrapped, profitable tool, which is a lovely thing to be able to say about an email platform built by a tiny team.

Who will love it

Plunk is made for founders and developers who would rather wire up one API than three. The cloud version is EU-hosted and GDPR compliant, supports custom domains with DKIM, tracks opens, clicks and conversions, and can even process inbound email. Pricing follows emails sent rather than list size, with unlimited contacts, so a growing user base does not quietly push you into a bigger plan. That model fits SaaS products well, where the contact list often grows faster than the send volume.

The best way to start

Open a free cloud account, which comes with a monthly email allowance and the full feature set, then hook up your domain and send your first transactional email from the API. If you want total control, pull the Docker image and self-host it on your own infrastructure, where there are no per-email costs from Plunk at all.

Three email tools folded into one tidy open source package, with a bill that only moves when you hit send.

The verdict