What does Stalwart replace?

Stalwart is a free alternative to Fastmail ($60/yr).

Is Stalwart open source?

Yes. Stalwart is licensed under AGPL-3.0, an OSI-approved open-source license.

Yes (self-hosted server; web UI).

Yes. Stalwart is a server app you run on your own server, and its repository includes Docker files.

A free, open-source alternative to Fastmail. Switching saves $60/yr at list price.

Checked Oct 17, 2026 · How we check

Self-hosted server

Replaces it Active Open source · AGPL-3.0 Linux Self-hostable

stalwartlabs/stalwart15.1k★last push Oct 15, 2026checked Oct 17, 2026

Running a mail server needs a clean-IP VPS with port 25 open, deliverability is on you, and webmail is a separate install.

Imports your data: move mail over IMAP with standard tools; contacts and calendars via vCard/ICS files

Self-host

Runs on your own Linux server, with Docker files in the repo. Setup docs are on stalw.art.

What does Stalwart replace?: Stalwart is a free alternative to Fastmail ($60/yr).
Is Stalwart open source?: Yes. Stalwart is licensed under AGPL-3.0, an OSI-approved open-source license.
Does Stalwart run on Linux?: Yes (self-hosted server; web UI).
Can you self-host Stalwart?: Yes. Stalwart is a server app you run on your own server, and its repository includes Docker files.