For most Mac users a free open-source diff app now covers side-by-side file and folder comparison, and some add three-way merge and Git support. Pay for a commercial tool when you need image, table or binary comparison, a licence that also covers Windows, or support for an older or newer macOS than the free apps run on.
Which diff tool should you put on your Mac? For most people, one of the new free, open-source native apps, with a paid tool kept for image and table comparison, a licence that also covers Windows, or an older macOS. A small wave of those free apps has arrived recently, so the question is no longer whether to pay but what paying gets you.
Run the test below on two or three candidates and the choice usually makes itself.
The test: an hour, two folders, one conflict
Build a small set of awkward differences on purpose, then see which tool shows them clearly. Use a real project folder you know well.
- Duplicate the folder in Finder so you have project and project copy.
- In the copy, edit three lines in one text file, then cut a block of about forty lines and paste it further down the same file.
- In a second file, convert the indentation from tabs to spaces without touching anything else.
- Rename one file, delete another and add a new one.
- Open one image in Preview, export it at a lower quality and save it over the original in the copy.
- Compare the two folders. Does the tool flag the moved block as a move or as a delete and an add? Can you tell it to ignore whitespace so the re-indented file drops out? Does it show the image as different, and can it show you where?
- Now make a merge conflict. In a Git repository, edit the same line two different ways on two branches, merge them, then run
git mergetooland see whether the tool opens a three-way view you can resolve in one pass.
You'll learn three things fast: whether the tool handles folders as well as files, whether its whitespace and image handling are any good, and whether it fits into Git without a fight. Those are the three forks that matter.
Free, one-off or rented
There are now four ways to pay for a Mac diff tool, and they suit different people.
- Open source. Three apps on this list are free under the MIT licence. You get the source, no account and no renewal. You also get whatever a small project can maintain, so check how recently it was updated.
- Free with a paid upgrade. Core features cost nothing and a one-time in-app purchase unlocks the heavier tools, such as executing a folder sync or deeper image comparison.
- A one-off licence. Pay once, use it for good. Some include a set period of updates, after which you keep the version you have.
- A subscription. Monthly or yearly, often with a team tier. You're paying for continuous updates and, in some cases, use across several devices.
The paid tools all offer a trial, so there's no reason to buy blind. On the vendors' own pages this month, per-user licences start at $35, professional editions go up to $269, and the subscription option starts at $8 a month, against nothing at all for the open-source apps. If you diff a few files a month, that gap buys you very little. If you resolve merges daily, it might.
Text only, or folders and images too
Every tool here compares text side by side. The split comes after that. Every app on this list compares folders too, free ones included, which is a big shift. Image comparison is rarer: two of the paid apps and two of the free ones offer it. One app compares tables and one compares binary files.
Writers and editors comparing two drafts need far less than they think: a clear side-by-side view with word-level highlighting is the whole job. Developers need three-way merge. Designers swapping exported assets need image comparison. Sysadmins comparing config directories on two machines need folders, whitespace control and ideally a sync step.
Wiring it into Git
A diff tool earns its keep when Git hands it work. Run git difftool --tool-help and Git lists the tools it already knows by name on your machine. For any of those, two commands set it as your default:
git config --global diff.tool NAME and git config --global merge.tool NAME
After that, git difftool opens each changed file in the app, and git difftool --dir-diff hands over the whole commit as two folders at once, which is far nicer than clicking through file by file. For a tool Git doesn't know, you point difftool.NAME.cmd at the app's command-line helper; check the app's own documentation for the exact line.
Three apps here state Git support outright, and one of the free ones says it opens Git conflict files directly. If you spend more time in a Git client than on the command line, check which diff tools your client can call; I've compared the Git GUIs separately.
Check your macOS version before anything else
This is the fork people miss. Minimum macOS versions on this list run from macOS 10.12 at one end to macOS 26 at the other, with two free apps needing macOS 14 and one paid app needing Sequoia. Araxis Merge's latest release lists support for macOS 27.
Open the Apple menu, choose About This Mac and note the version before you download anything. An office with a mix of older and newer Macs may find the newest free apps simply won't open on half the machines.
Free, open-source Mac diff apps
MacMerge
Fans of WinMerge on Windows will feel at home here: side-by-side file and folder comparison with a three-way merge view, written natively for the Mac.
Mergeloom
An open-source diff and merge app for comparing and merging files and folders side by side, with nothing to sign up for.
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Differentialis
Written in SwiftUI with Git built in, this compares and merges text, images and folders for people already running the newest macOS.
MergeDock
A Mac App Store download covering text, folders, images and binary files, with two-way editing, three-way merge and Git difftool use.
Paid diff and merge apps
Kaleidoscope
Text, image and folder comparison with three-way merge and deep Git integration, in a native app licensed across several devices.
Changes
Owners of older Macs have a native file and folder comparer here that merges in either direction and runs on releases far back.
Beyond Compare
Mixed Windows, Linux and Mac teams use this to compare folders, text, images and tables with the same tool everywhere.
Araxis Merge
Two and three-way comparison, merging and folder synchronisation, sold under a licence that covers both macOS and Windows.
What I'd install, for the work you do
You compare the odd file or draft: an open-source app. It's free, it's native and it'll do everything you need. Try two and keep the one whose highlighting you can read at a glance.
You write code and merge branches daily: a tool with a three-way merge view and stated Git support, set as your default difftool and mergetool. Start with an open-source app that has a three-way view and opens Git conflict files; pay only if the test above shows the paid tool resolving conflicts faster.
You compare folders of images or exported assets: a tool with image comparison, which on this list means one of two paid apps or one of two newer free ones.
Your team spans Windows and Mac: a cross-platform tool, so everyone's looking at the same view and you're not training people on two apps.
You're on an older Mac: check minimum versions first and pick from what installs, not from what's newest.
Do you make diff and merge tools for the Mac? Tool makers can ask to be considered for a featured place on this list.
And if most of your comparing happens inside an editor, you may not need a separate app at all. VS Code opens a diff with code --diff fileA fileB, and you'll find other options in my round-ups of text editors for Mac and VS Code alternatives.
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