There are 2 open-source alternatives to Zimbra in this directory. The most popular is Stalwart with 12.3k GitHub stars, followed by Modoboa(3.5k stars). All are open source, free to use, and many can be self-hosted.
| # | Tool | Stars | Language | License |
|---|---|---|---|---|
| 1 | Stalwart Stalwart is an all-in-one mail and collaboration server designed to be secure, scalable, and highly compatible with a wide range of protocols including IMAP, JMAP, SMTP, CalDAV, CardDAV, and WebDAV. It provides enterprise-class communication and groupware functionality in a single unified solution. | 12.3k | Rust | — |
| 2 | Modoboa Modoboa is an open-source platform that simplifies mail hosting by providing a modern and user-friendly web interface for managing email domains, mailboxes, and aliases. It features integrated administration, security enhancements, and extensibility for hassle-free email server management. | 3.5k | Python | ISC License |
Stalwart is an all-in-one mail and collaboration server designed to be secure, scalable, and highly compatible with a wide range of protocols including IMAP, JMAP, SMTP, CalDAV, CardDAV, and WebDAV. It provides enterprise-class communication and groupware functionality in a single unified solution.
Modoboa is an open-source platform that simplifies mail hosting by providing a modern and user-friendly web interface for managing email domains, mailboxes, and aliases. It features integrated administration, security enhancements, and extensibility for hassle-free email server management.
The top three are Stalwart(12.3k stars), Modoboa(3.5k stars). All are open source and free to use.
Yes. Every tool listed here is open source and free to use in your own projects. Many can be self-hosted on your own infrastructure, which means no subscription fees and full control over your data.
Many of the alternatives listed are self-hostable. Each tool's page lists hosting details, system requirements, and licensing terms.
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