The Freeman Calendar was created by Litmus A Freeman in the year 2012 Gregorian and is known mainly by it's descriptive name, the Universal Celestial Calendar (UCC).
The UCC has a page on this Calendar Wiki site as well as many online resources on its own websites.
Litmus created another 'Freeman Calendar' as an alternative version of the UCC on 22 Aries♈ 13521 UCC (13th April 2020 Gregorian) with the aim of better synchronising the UCC's 12 'Triads' (30 day months) with their 12 associated Western Tropical Zodiac Signs (30° months) in terms of ecliptic longitude. He calls this sister version the UCC 'Peacock's Tail' Calendar due to its graphical appearance.