MAC - Diff Tools on macOS

Compare Folders (Free)
QuickCompare
FileMerge (Apple's own merge tool)
Beyond Compare
Araxis Merge ($)
DeltaWalker
Kaleidoscope
Free Alternatives: In case you're looking for a free alternative to the standard FileMerge app, you should also have a look at P4Merge and DiffMerge.
Integrations: Another aspect to watch out for is integrations: before choosing your favorite tool, you should make sure that it plays nicely with the rest of your tool chain. I can already confirm that all of the mentioned tools work seamlessly at least with Tower, our own Git client.If you don't need the power of a dedicated Diff tool application, the integrated diff views in Tower might even be sufficient for you:
IDE: PhpStorm

Compare Folders – Diff Tools on macOS