Plunk
Open source email platform
The Lens
By Erik Loyd, SaaS CEO and former COO/CFO of an AWS Premier Partner.
Updated Mar 2026
Plunk handles both transactional emails (welcome emails, order confirmations) and marketing emails (newsletters, drip campaigns) from one open source platform you control. Self-host it, connect your SMTP or AWS SES, and you've got email infrastructure without paying per-email fees to Mailchimp or SendGrid.
The dashboard is clean. Manage contacts, build emails with a visual editor, set up automations, track opens and clicks. It's what you'd expect from a modern email platform, minus the monthly bill.
AGPL-3.0, TypeScript. They also offer a hosted version.
The catch: AGPL license means if you modify Plunk and offer it as a service, you must open source your changes. The project is relatively small compared to alternatives: fewer integrations, less battle-testing at scale. And email deliverability is hard. Self-hosting email means managing SPF, DKIM, DMARC, IP reputation, and bounce handling. Plunk makes the app layer easy but can't solve the deliverability puzzle for you.
Free vs Self-Hosted vs Paid
free self hosted paid cloudFree (AGPL-3.0): Full platform: transactional email, marketing campaigns, automations, contact management, analytics. Self-host with Docker. AGPL means modifications must be open-sourced if you offer it as a service.
Plunk Cloud:
- Free tier: limited sends (check useplunk.com for current limits)
- Paid: usage-based pricing for higher volumes
Self-hosting cost: a $10-20/mo VPS runs Plunk. You still need an email sending service. AWS SES at $0.10 per 1,000 emails is the cheapest option. Total self-hosted: $10-25/mo for infrastructure + pennies per email.
Compare to SendGrid ($15-90/mo), Mailchimp ($13-350/mo), or Resend ($20/mo for 50K emails). Self-hosted Plunk + SES is dramatically cheaper at scale.
Self-host free + ~$0.10/1K emails via SES. Beats most paid email platforms on cost.
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