Compare software

grommunioCyrus IMAP
Freemium

Open source, with paid plans listed on the pricing page.

 Free

Free and open source.

Linux, Web, Self-hosted Linux, Self-hosted
  • Native MAPI, EWS and EAS support for Outlook and mobile clients
  • Mail, calendars, chat, video and files on one platform
  • Mail, calendars and contacts in one server
  • JMAP support alongside IMAP
  • Running a groupware server requires administration skills
  • Some features may depend on paid plans
  • Complex to configure compared with all-in-one servers
  • No bundled webmail
Self-hosted, Hosted service Self-hosted
Open source Open source
License not stated License not stated
Not stated if an account is needed No account needed
Not stated if it works offline Not stated if it works offline

Checked October 1, 2026

Checked September 24, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.