if i had to pick one the most beautiful piece of software i'd have to say git. 1m lines of code packed in 20mb, no user interface, used by every single project that matters from tiny to huge, and it just works. created by Linus Torvalds out of necessity 20 years ago, maintained since then by the guy Linus put in charge plus thousands volunteers contributing code.
Torvalds says that he names every project after himself. linux ~ Linus, git - 'an unpleasant or contemptible person'
https://git-scm.com/