Duplicate files
DeltaWalker
File and Folder Comparison and Synchronization: https://www.deltawalker.com/
install fdupes on mac
brew install fdupes
find duplicates
fdupes .
find and delete duplicates
preserve the first file in each set of duplicates and delete the rest without prompting the user
fdupes -dN .
recursive:
fdupes -dNr .
dupeGuru Picture Edition
This great tool finds duplicate images based on content.