What is Plunk used for?

Plunk is an open-source email platform for transactional email, campaigns and workflow automation, offered as a self-hostable alternative to SendGrid and Mailgun. It is a good fit for sending app notifications through an API, running newsletters from your own infrastructure and replacing SendGrid or Mailgun.

Is Plunk open source?

Yes. Plunk is open source under the AGPL-3.0 licence. Its source code is on GitHub at useplunk/plunk and is written mainly in TypeScript.

Yes. Plunk is open source, so the software itself is free to use. A managed cloud version is also available.

Can I self-host Plunk?

Yes. Plunk can be self-hosted on your own server or infrastructure.

What is Plunk an alternative to?

Plunk is an open-source alternative to SendGrid, Mailgun, Resend and Loops. Other open-source alternatives to SendGrid include Notifuse, Postal and BillionMail.

Is Plunk actively maintained?

Yes. The most recent commit to Plunk was on 2 October 2026, and the latest release is v0.15.0, published on 20 September 2026. The project has 5.5k stars on GitHub.

Plunk: open-source alternative to SendGrid, Mailgun, Resend

About Plunk

Plunk is an open-source email platform that combines transactional email, marketing campaigns and workflow automation in a single product. Developers can send messages from an API with templates and variable substitution, or use Plunk as an SMTP relay so that existing tools and frameworks can send through it.

Marketing features include campaigns for newsletters and product updates, dynamic segments, and contact management with custom fields and activity history. Workflows add triggers, delays and conditional logic, analytics track opens, clicks and bounces, custom domains are verified with DKIM and SPF, and inbound emails can be received and routed with custom rules.

Plunk is positioned as an open-source, self-hosted alternative to services such as SendGrid, Resend and Mailgun. It is licensed under AGPL-3.0, written in TypeScript, and can be deployed from an official Docker image following the project's documentation. The README cites a rate of $0.001 per email with no contact limits.

Key features

Transactional email API with templates
SMTP relay for existing tools
Campaigns for newsletters and updates
Workflow automation with delays and conditions
Dynamic contact segments
Open, click and bounce analytics
Inbound email routing
Custom sending domains with DKIM and SPF

Good fit for

→Sending app notifications through an API
→Running newsletters from your own infrastructure
→Replacing SendGrid or Mailgun

Built with: TypeScript
Tags: email; transactional-email; smtp; email-marketing; newsletter; automation; self-hosted; typescript

Plunk: questions and answers

What is Plunk used for?: Plunk is an open-source email platform for transactional email, campaigns and workflow automation, offered as a self-hostable alternative to SendGrid and Mailgun. It is a good fit for sending app notifications through an API, running newsletters from your own infrastructure and replacing SendGrid or Mailgun.
Is Plunk open source?: Yes. Plunk is open source under the AGPL-3.0 licence. Its source code is on GitHub at useplunk/plunk and is written mainly in TypeScript.
Is Plunk free?: Yes. Plunk is open source, so the software itself is free to use. A managed cloud version is also available.
Can I self-host Plunk?: Yes. Plunk can be self-hosted on your own server or infrastructure.
What is Plunk an alternative to?: Plunk is an open-source alternative to SendGrid, Mailgun, Resend and Loops. Other open-source alternatives to SendGrid include Notifuse, Postal and BillionMail.
Is Plunk actively maintained?: Yes. The most recent commit to Plunk was on 2 October 2026, and the latest release is v0.15.0, published on 20 September 2026. The project has 5.5k stars on GitHub.