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Self-hosted

Open-source Resend alternatives you can self-host

Six real projects, from a drop-in replacement for Resend's API to a full mail server you run yourself. Licences, dependencies, and the part the READMEs skip: once you self-host, deliverability is your job.

6 projects Checked 2 August 2026 AGPL and MIT
Read this first

The bill is not the hard part

Every project here will cut your sending cost. Amazon SES charges $0.16 per 1,000 emails, so the volume Resend sells for $35 a month costs about $16 in raw sending. That arithmetic is real and it is why this search exists.

The arithmetic that doesn't appear anywhere is reputation. A hosted provider is partly a product and mostly a relationship with the mailbox providers — shared IP pools that are already warm, an abuse desk that gets you off a blocklist, engineers who notice a Gmail deferral pattern before you do. Self-hosting hands all of that to you.

That's a fine trade if you're sending internal notifications, if you have someone who enjoys this, or if data ownership is the actual requirement. It's a bad trade if the email in question is a password reset for paying customers and nobody on the team wants to own an IP warm-up schedule.

Two of the six — useSend and FreeResend — split the difference. They put a dashboard over Amazon SES, so AWS keeps the reputation problem while you keep the interface and the data.

Operationally

What each one asks of you

The difference between a weekend and a permanent responsibility is mostly in this table.

ProjectSends throughYou operateDrop-in for Resend's API
useSendYour own Amazon SES accountPostgres, Redis, the app container, DNSNo — its own API shape
PlunkSMTP you configure, or Plunk CloudPostgres, Redis, the app containerNo — its own API shape
FreeResendYour own Amazon SES accountPostgres, Node 18+, DNS (DigitalOcean can automate it)Yes — set RESEND_BASE_URL and the Resend SDK works
NotifuseSES, Mailgun, Postmark, Mailjet, SparkPost or plain SMTPPostgres, the Go binary, the React consoleNo — provider-agnostic layer above sending
listmonkAny SMTP providerPostgres and one Go binaryNo — list and campaign manager, not a send API
PostalItself — it is the mail serverDatabase, message queue, IPs, reverse DNS, reputationNo — SMTP and its own HTTP API

From each project's own README and documentation, 2 August 2026.

The projects

Six open-source options, in detail

01AGPL-3.0

useSend (formerly Unsend)

Best for: Self-hosters who want a Resend-shaped dashboard on top of their own SES account

The best-known open-source answer to this search. It wraps Amazon SES with a dashboard, contacts, campaigns and webhooks, so you pay AWS rates and keep the UI.

Starts at
Free to run; you pay Amazon SES for the sending
Free tier
Self-hosted — the software is free
Marketing
Included: contacts, campaigns and transactional in one app
License
AGPL-3.0
Data region
Wherever you deploy it
What it does well
  • SES pricing with a real interface on top.
  • Transactional and marketing, REST API and SMTP, webhooks and inbound.
  • Docker images and a one-click Railway deploy.
What to watch for
  • Still described as beta by its own maintainers.
  • Bring your own AWS account, DNS, Postgres and Redis — and your own on-call.
  • AGPL-3.0 has real obligations if you build a product on top of it.
02AGPL-3.0

Plunk

Best for: Open-source teams who want campaigns and automation, not just an API

Transactional sending, newsletters and a workflow automation builder in one AGPL codebase, with a hosted pay-as-you-go option if you'd rather not run it.

Starts at
Self-host free, or $0.001 per email on Plunk Cloud
Free tier
Self-hosted — the software is free
Marketing
Included: campaigns plus a trigger-and-condition automation builder
License
AGPL-3.0
Data region
Wherever you deploy it
What it does well
  • Automation flows out of the box, which most open-source options lack.
  • $0.001/email hosted pricing is genuinely pay-as-you-go — no monthly floor.
  • SMTP relay, so existing tooling keeps working.
What to watch for
  • Smaller ecosystem than the commercial APIs; fewer integrations.
  • AGPL-3.0 again — read it before embedding.
  • Self-hosting means owning deliverability, which is the hard part.
03MIT

FreeResend

Best for: Getting off Resend without touching application code

A deliberately narrow project: a self-hosted server that speaks Resend's API. Point the official Resend SDK at it with RESEND_BASE_URL and your sends go through your own SES account instead.

Starts at
Free to run; you pay Amazon SES for the sending
Free tier
Self-hosted — the software is free
Marketing
None — transactional only
License
MIT
Data region
Wherever you deploy it
What it does well
  • Drop-in: the official Resend Node SDK works against it unchanged.
  • MIT licensed, so no AGPL obligations.
  • Optional DigitalOcean integration creates the DNS records for you.
What to watch for
  • Small project — a few hundred stars and a short commit history. Read the code before you depend on it.
  • Needs Amazon SES, PostgreSQL and Node 18+ that you operate.
  • No campaigns, no contacts, no automation.
04AGPL-3.0

Notifuse

Best for: Self-hosters who want a visual builder and to keep their existing sending provider

Go and React, AGPL, and provider-agnostic: it drives SES, Mailgun, Postmark, Mailjet, SparkPost or plain SMTP rather than replacing them. Campaigns, A/B tests and segmentation on top.

Starts at
Self-host free, or Notifuse Cloud from $16/mo
Free tier
Self-hosted — the software is free
Marketing
Included: visual builder, scheduling, A/B tests, segmentation
License
AGPL-3.0
Data region
Wherever you deploy it
What it does well
  • Bring your own delivery provider — switching costs you a config change, not a migration.
  • Liquid templating, REST API and webhooks for the developer side.
  • A hosted tier exists if self-hosting stops being fun.
What to watch for
  • You still need a sending provider underneath; this is the layer above it.
  • Younger and smaller than listmonk.
  • AGPL-3.0.
05AGPL-3.0

listmonk

Best for: Newsletters at volume, on hardware you already pay for

A single Go binary and a Postgres database that will happily push millions of newsletters through whatever SMTP you point it at. Mature, fast, and unapologetically list-first.

Starts at
Free to run; you pay your SMTP provider for the sending
Free tier
Self-hosted — the software is free
Marketing
That's the whole product: lists, subscribers, campaigns, templates
License
AGPL-3.0
Data region
Wherever you deploy it
What it does well
  • The most established project here — over 22,000 GitHub stars and years of production use.
  • One binary plus Postgres. No Redis, no queue broker, no Kubernetes.
  • Handles very large lists on modest hardware.
What to watch for
  • It is not a transactional email API product — that's not what it's for.
  • Bring your own SMTP and your own deliverability.
  • The admin UI is functional rather than beautiful.
06MIT

Postal

Best for: Running your own mail server on purpose

Not an SES wrapper — a complete MTA that sends and receives. If you want to own the IPs, the queues and the reputation, this is the mature option.

Starts at
Free to run; you pay for servers and IPs
Free tier
Self-hosted — the software is free
Marketing
None; it's infrastructure
License
MIT
Data region
Wherever you deploy it
What it does well
  • MIT licensed, ~16,700 stars, years of production use.
  • Sends and receives — a full mail platform, not a relay.
  • Total control over IPs and routing.
What to watch for
  • You now own IP warm-up, blocklist removals and abuse handling. This is a job, not a weekend.
  • Needs a database, a message queue and correctly configured DNS.
  • Nobody to call at 3am when Gmail starts deferring you.
Licensing

AGPL is not a detail

Four of the six — useSend, Plunk, Notifuse and listmonk — are AGPL-3.0. Running an unmodified copy to send your own company's email is the ordinary case and raises nothing. The clause that matters is the network one: modify the software, let users interact with it over a network, and the licence expects you to offer those users the modified source.

If you're planning to fork one of these into a product you sell, that's a conversation with a lawyer rather than a blog post. FreeResend and Postal are MIT, so if you want to embed and modify freely, start there.

The other direction

If the answer turns out to be "not this"

Plenty of people arrive at this search wanting lower cost and ownership, work through the operational column above, and decide the hosted price was reasonable after all. That's a legitimate outcome of the research, so here is the honest version from our side.

Email Bump is not open source. There is no self-hosted build and no public repository to read. What we do instead is remove the reason most people are here: one contact-priced plan covers campaigns, automated flows, segments, the transactional API and SMTP together, starting at $19/mo for 10,000 contacts, with 5,000 contacts and 5,000 emails free. And because the CLI and MCP server cover the same surface as the API, the account is scriptable end to end even though the source isn't yours.

If reading the source is the requirement rather than the price, useSend is where we'd point you. It's the closest open-source match to what Resend does, and it is upstream of most of the others in this search.

FAQ

Self-hosting email, asked and answered

Is there an open-source alternative to Resend?

Yes, several, and they split into three groups. Wrappers over Amazon SES that give you a Resend-like dashboard: useSend and FreeResend. Full platforms with campaigns and automation: Plunk, Notifuse and listmonk. And actual mail servers you run end to end: Postal.

Which group you want depends on whether you're trying to cut the bill, own the data, or run the infrastructure. Those are different projects.

Is there a self-hosted Resend alternative that uses the same API?

FreeResend. It implements Resend's API surface, so pointing the official Resend Node SDK at your own instance with RESEND_BASE_URL works without touching application code. It's MIT licensed and runs on Amazon SES with a Postgres database.

It is also a small project — a few hundred GitHub stars and a short commit history. Read the source before you make it load-bearing, and keep a fallback provider configured.

Is self-hosting email actually cheaper?

On the invoice, yes, dramatically. Amazon SES is $0.16 per 1,000 emails, so 100,000 emails a month costs about $16 in sending plus a small server. The same volume is $35/mo on Resend's Pro plan and $90/mo on Scale.

The cost that doesn't appear on the invoice is deliverability. When Gmail starts deferring your mail, there is no support queue — there's you, at 11pm, reading Postmaster Tools. Teams who value that time at anything close to its real rate usually find the hosted price was fine.

What does the AGPL mean for my product?

useSend, Plunk, Notifuse and listmonk are all AGPL-3.0. The practical consequence is that if you modify the software and let users interact with it over a network, the licence expects you to offer them the modified source. Running an unmodified copy for your own sending is the ordinary case and is fine.

If you plan to build a product on top of one of these, read the licence properly or pick an MIT-licensed option — FreeResend and Postal are both MIT.

Which open-source option should I pick?

Want Resend's ergonomics on your own SES bill: useSend. Want your code to stay literally unchanged: FreeResend. Want newsletters at volume on hardware you already have: listmonk. Want campaigns and automation in one AGPL codebase: Plunk. Want to keep your current sending provider and add a builder on top: Notifuse. Want to run your own mail server on purpose: Postal.

The hosted option

Or skip the on-call rotation

Marketing and transactional on one plan, US sending on Amazon SES, 5,000 contacts and 5,000 emails free. Not open source — the trade is that nobody pages you about a blocklist.

Start free Read the API docs

Keep reading

All Resend alternativesSixteen options, what each costs, and who each one is actually for.Free alternativesEvery free tier compared on the limit that bites first.Email Bump vs ResendThe head-to-head, including the numbers that don't flatter us.Email Bump pricingWhat contact-based pricing costs at every list size.