Czkawka

Czkawka clears out the mess that builds up over years of copying folders around. It finds exact duplicates, photos that are near matches at different sizes, empty folders, large files, broken shortcuts and music with matching tags.

It replaces the duplicate cleaners sold on Windows, most of which limit how much you can delete unless you pay. This one has no limit and costs nothing.

Be careful with it. Results are shown as groups with checkboxes, there is a select-all-but-one helper, and once you confirm the deletion the files are gone. Run a backup first, look at what you have ticked, and never let it loose on a system folder.