Replace / Mandrill
Best free Mandrill alternatives (open source, self-hosted) 2026
The best open-source alternative to Mandrill is Plunk (or goposta/posta) with Resend, self-hosted on Railway. Own the list in PocketBase, send with Resend, use Plunk or Posta when you want a full newsletter app. Mailchimp, Mailgun, SendGrid, and Postmark without the list or message meter.
Estimated save $1,800 a year.
Open the stackStart on Railway
How Mandrill compares
| Mandrill | Plunk or Posta + Resend | |
|---|---|---|
| Pricing model | Hosted subscription | Open-source or fair-code license; you pay the host |
| Hosting | Vendor cloud | Self-hosted on Railway or any VPS |
| Rough monthly cost | Public list price not verified this run | Hosting only — no SaaS seat meter in this repo |
- Plunk
Open-source email platform
- goposta/posta
Self-hosted newsletter
- Resend
Delivery, audiences, broadcasts
- PocketBase
Signup mirror you own
FAQ
- What is the best free open-source Mandrill alternative?
- The best open-source alternative to Mandrill is Plunk (or goposta/posta) with Resend, self-hosted on Railway. Own the list in PocketBase, send with Resend, use Plunk or Posta when you want a full newsletter app. Mailchimp, Mailgun, SendGrid, and Postmark without the list or message meter.
- Is it free?
- The Plunk or Posta + Resend licenses are open source or fair-code. You still pay hosting (Railway or any VPS) and any APIs the stack calls. There is no Mandrill seat or task bill on this path.
- Can I migrate from Mandrill?
- Yes. Start with the workflows or data you actually use, then cut over. The Plunk or Posta + Resend stack page has the agent prompt and the cost table; most teams rebuild the slice that matters and leave old Mandrill links until they expire.
- How do I deploy it?
- Open the Plunk or Posta + Resend stack, copy the agent prompt, and deploy on Railway (one service, PORT, and a volume when the app needs disk). This site already stores subscribers in PocketBase and optionally adds them to a Resend audience. Plunk/Posta is the upgrade path.
- What does this replace?
- Mailchimp / Mailgun / SendGrid / Postmark. The published small-team estimate on this stack is $1,800 a year.
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