DeltaWalker is far and away the best file comparison tool I've ever used.
Blindingly fast on both Mac and Windows. I use it to compare massive directory trees in mere seconds.
Tons of useful features. Shows a graphical side-by-side view that allows you to selectively resolve differences, accepting the new or old version, or just editing the files directly. Also does a good job of comparing Word docs, Excel spreadsheets, PDF files, and even images. Can be invoked from a command line or script, so comparisons can become part of an automated workflow. Picks up file changes that occur on disk while it's already running, and prompts unobtrusively for whether to reload.
I'm a computer programmer for over 3 decades, and have always been an extreme power user of diff tools. I've built them into my workflows so I often invoke them dozens or even hundreds of times per day. I recommend DeltaWalker to all of my colleagues, and they are always very impressed.
The support team is fantastic. If I ever have a question, find a bug, or want a new feature I just email firstname.lastname@example.org. Within a few hours, I have a clear, concise, accurate answer to my question. Within a few days, I usually have a new version of the software with the bug fixed or feature added.
I've used DeltaWalker for over 10 years, and never found anything that's anywhere near as good.
I think many of the other comments I've read here are either inaccurate or obsolete. For example:
- DeltaWalker now comes with its own bundled version of Java, so it's unaffected by any other Java version you may have installed and works fine even if you don't have any version of Java installed. So, Brightshade's comment (certainly once a problem, as I saw for myself a few years ago) is no longer true.
- Works fine on all versions of Mac, including Catalina (and Big Sur -- see below). So the comment from Alec124c41 appears to be obsolete too. I was discouraged at first to see that it wouldn't install under macOS Big Sur, so I emailed email@example.com as usual. Within a couple days, they sent me a link to a pre-release version that does. They claim there are still a few cosmetic nits to be fixed before the official release of that version (2.5.9), but I haven't seen any. Works perfectly for me!
- Has been continuously updated for at least 12 years, perhaps much longer. So, I think Brandondrew' comment in inaccurate. I've installed and used lots of updated versions over the years. See the historical release notes at: https://deltawalker.com/new-and-noteworthy
If you see anything different, please reply to this comment, which will cause your reply to be emailed to me so I'll be sure to see it. Or just send email to the support team at the address shown above. I'm a huge fan, but not a member of the Deltopia team, so I can share my experience and tips, but I won't be nearly as informed as they are.