I have recently downloaded PuTTY as a possible way to log into my NAS (I have been using FileZilla FTP Client to upload files, as I find it a miles better way to upload files than Windows Explorer (failed transfers don't stop the transfer process, and if there are any you can just transfer them back into the queue and try again), but for some reason it stopped working), and I was impressed by the fact that the maintainer is Simon Tatham, of Puzzle Pack fame!
(I use his Puzzle Pack on all three of my devices.)