Stalwart

Open-source mail and collaboration server with JMAP, IMAP4, POP3, SMTP, CalDAV, CardDAV and WebDAV support. Written in Rust, designed to be secure, scalable, and easy to operate

Category: Open Source
Funding: Bootstrapped

Sources, checked Sep 26, 2026. A fact that is missing is one we could not source, not a zero.

Summary: the company’s own description, stalw.art
Funding: news.ycombinator.com — “Stalwart's development has been largely self-funded”

Category is our own classification. Spotted something wrong? Tell us.

Frequently asked questions

What does Stalwart do?

Open-source mail and collaboration server with JMAP, IMAP4, POP3, SMTP, CalDAV, CardDAV and WebDAV support. Written in Rust, designed to be secure, scalable, and easy to operate

Where is Stalwart based?

Location for Stalwart has not been disclosed publicly.

How much has Stalwart raised?

Stalwart is bootstrapped. We have not verified a funding amount.