Plunk
An open-source email platform for SaaS.
In short
- What it is: Email, 4k+ GitHub stars, licensed AGPL.
- Replaces: Sendgrid — around $240/year saved.
- Installed for: $149 on your own server — you own it, no monthly platform fee.
- Licence: AGPL. AGPL obligations apply — self-host is fine; comply if offered as a service.
$240
replaces per year
$1,200
saved over 5 years
$149
one-time install (yours forever)
48h
delivery
Plunk vs the tools it replaces.
| Feature | Commercial tool | Plunk (self-hosted) |
|---|---|---|
| Monthly cost | $20/mo | Your compute only |
| Branding | Vendor brand | See licence |
| Data | Vendor-hosted | On your server |
| Licence | Proprietary | AGPL |
Replaces
- Sendgrid — ~$20/mo
Licence posture
AGPL. AGPL obligations apply. Self-hosting is fine; comply if you offer it as a service, or buy a commercial licence.
AGPL obligations apply — self-host is fine; comply if offered as a service.
Turn it into a business.
Self-host for a client's internal use and charge for the install. If you modify and offer it as a network service, comply with AGPL — or buy a commercial licence.
Best for
Install difficulty
medium
The install, step by step.
Provision VPS + Docker
Configure secrets + provider keys
Database + storage setup
Branding + domain
HTTPS + backups
Smoke test + handover
Watch a Plunk install.
We generate an architecture diagram of the repo and walk through the deployment. Enter your name and email to unlock the demo.
Install Plunk — $149.
Flat fee, delivered in 24–48 hours, on your own server, with HTTPS, backups and the AI keys wired.
Plunk: common questions
What does Plunk replace?
Sendgrid — about $240 a year in subscriptions you stop paying.
How much does it cost to run Plunk?
No licence fee — it ships under AGPL. You pay only for your own server and any model/API keys. We install, harden and hand it over for a one-time $149.
Can I white-label and resell Plunk?
AGPL obligations apply. Self-hosting is fine; comply if you offer it as a service, or buy a commercial licence. AGPL obligations apply — self-host is fine; comply if offered as a service.
How hard is the install, and how long does it take?
We rate it medium. Delivered in 24–48 hours on your own server, with HTTPS, backups and the AI keys wired.
What do I actually own after installing Plunk?
The running app, your data and the brand. No monthly platform fee and no per-seat pricing — you own it outright.
Other repos people install with Plunk.
Listmonk
A fast, self-hosted newsletter and mailing list manager.
AGPL · 17k+★
EmailMautic
Open-source marketing automation.
GPL · 8k+★
EmailPostal
A complete mail server for sending and receiving.
MIT · 13k+★
Chat UILibreChat
A full multi-model ChatGPT-style interface with auth, multi-user and presets.
MIT · 40k+★
Chat UIOpen WebUI
A polished local/remote chat workspace with RAG and tools built in.
BSD-3 (older) / branding-retention terms (newer) · 90k+★
Doc chatAnythingLLM
Private RAG chat over your own documents, desktop and server.
MIT core · 40k+★