List folders along with the space they use (useful for finding out what is taking up sooo much space!): [[https://jam-software.com/treesize_free/|TreeSize Free]]

Compare files/contents of 2 folders (useful for checking if two directories are identical, such as for backup verification; or to find out what is missing is one or the other): [[http://winmerge.org|WinMerge]]

Fine duplicate files (useful for...): [[https://dupeguru.voltaicideas.net|DupeGuru]]