Best duplicate file checker for quickly finding duplicates on Windows or Mac?

Personally I am using https://www.tkosoft.com/products/clonescan/ it's Windows-only, so it'd only cover half of what you need (your Windows 11 laptop, not the Mac). For the Windows side, it does name/size/SHA-1 hash matching, exports results to CSV so you can review before deleting anything, and moves duplicates to the Recycle Bin instead of permanent delete — useful for photos/docs since you can undo a bad call. For the Mac side you'd still need something separate like dupeGuru, which a few others here have mentioned and which also covers Windows if you'd rather run one tool on both.