The 4.0 version of CalendarX for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free software for Mac is lupa zurven. The following version: 0.9 is the most frequently downloaded one by the program users. We recommend checking the downloaded files with any free antivirus.
From the developer:
USE THE EGGS! get CalendarX via egg or tarball at Pypi or dist.plone.org. CalendarX is a feature-rich calendar and event CMS built in python using Plone and Archetypes. Event categories (metacalendar) and more. Plone is a free and open source content management system built on top of the Zope application server. In principle, Plone can be used for any kind of website, including blogs, internet sites, webshops and internal websites.