This is an aggregation of the answers posted on SO's deleted clone, [Graphical diff for Mac OS X](http://stackoverflow.com/questions/187064/graphical-diff-for-mac-os-x). It includes links to each product, and the current price since last edit in USD.

Note that any links to SO will only be visible to users who can view deleted content, which requires either moderator privileges or 10k reputation on that site.

 - Sourcegear's [DiffMerge](http://sourcegear.com/diffmerge/), shareware
 - Joachim Eibl's [KDiff3](http://kdiff3.sourceforge.net), free
 - Black Pixel's [Kaleidoscope](http://www.kaleidoscopeapp.com/), $69.99
 - Bare Bones Software's [TextWrangler](http://www.barebones.com), free
 - Araxis's [Merge](http://www.araxis.com/merge/index.html), $129 + $29/year
 - Deltopia's [DeltaWalker](http://www.deltopia.com/compare-merge-sync/macosx/), $39.95/$75.95
 - Kai Willadsen's [Meld](http://meldmerge.org), free
 - Weipin Xia's [DiffFork](http://www.dotfork.com/difffork/), $26
 - Biscade's [RoaringDiff](http://www.biscade.com/tools/diff/), free
 - [tkdiff](http://sourceforge.net/projects/tkdiff/), free

There were some other suggestions, which were not diff tools in their own right, which I will list below:

  - It (Beyond Compare) runs well in [Wine](http://www.winehq.org), but I miss the shell integration. - [Danyal Aytekin](http://stackoverflow.com/users/294855/danyal-aytekin), [May 11 '12, 13:01](http://stackoverflow.com/questions/187064/graphical-diff-for-mac-os-x#comment13654610_3193658)
  - Eclipse also has a fairly decent comparison mechanism. - [JeeBee](http://stackoverflow.com/users/17832/jeebee), [Oct 9 '08, 12:45](http://stackoverflow.com/a/187084)
  - P4Merge that comes with [Perforce](http://www.perforce.com) is pretty good and comes for free with perforce client. Both terminal and GUI version. - [amok](http://stackoverflow.com/users/149157/amok), [Jul 7 '10, 23:19](http://stackoverflow.com/a/3199634)
  - I had to use [Vim](http://www.vim.org) because most of diffs mentioned here do not understand UTF-8. - user184880, [Oct 6 '09, 9:56](http://stackoverflow.com/a/1524646)

That about wraps up that thread's merge into this one, as [covered here](http://meta.stackexchange.com/a/174071).