Beyond Compare - Beyond Compare allows you to compare files and folders.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
Sketch - Professional digital design for Mac.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.
Affinity Designer - Professional creative software, exclusively for Mac.