Google Calendar
Free
Google Calendar is a cloud based calendar from Google.
Zimbra Collaboration Suite
Freemium
Zimbra offers an open source email platform for the enterprise.
Microsoft Exchange Server
Commercial
Microsoft Exchange Server is a mail server and calendaring server.
Zoho
Free Personal
ZOHO Corporation offers online business, network, and IT infrastructure management applications, and software maintenance and support services.
Kopano
Open Source
Kopano is an open-source groupware application suite originally based on Zarafa.
OX Open-Xchange
Open Source
OX Open-Xchange is a web-based communication, collaboration and office productivity software.
Compare Kolab Community with alternatives
Compare Google Calendar and Kolab Community and decide which is most suitable for you.
Compare Zoho and Kolab Community and decide which is most suitable for you.
Compare Zimbra Collaboration Suite and Kolab Community and decide which is most suitable for you.
Compare Kopano and Kolab Community and decide which is most suitable for you.
Compare Microsoft Exchange Server and Kolab Community and decide which is most suitable for you.
Compare OX Open-Xchange and Kolab Community and decide which is most suitable for you.