I built these to run my own time and my own money, one piece at a time. Now you can use them too. An ant builds its nest the same way, piece by piece.
A file has one advantage a service can't match: nobody can take it back. You keep the copy you paid for, on your own disk, and it works the same in five years.
Each kit is written by hand, with no frameworks and no outside scripts, so there is nothing that can stop loading. When a browser change breaks something, the fix ships as a new version of the same file, free for everyone who bought it.