File synchronizer fra http://www.cis.upenn.edu/~bcpierce/unison/

2.48.4 beta zip binary til Windows er fra
https://www.irif.univ-paris-diderot.fr/~vouillon//unison/unison%202.48.4.zip

Best guess for a working zip is
unison-2.48.3.zip for Windows
Unison-OS-X-2.48.3.zip for Mac OS X