The Top Three Tools When Comparing Documents With a Mac

When you work with text, as you certainly do in law, you often need to be able to compare one text to another easily and quickly. Like lawyers, software developers routinely compare different versions of text (source code, not legal documents) as they work—but the way software developers typically go about this is very different, and arguably better, than the way lawyers typically go about this.

In software development, comparing one version of a file to another generally is not a separate step in a working process. There’s no “track changes,” and you don’t “run a redline.” Instead, comparisons are essentially already done, all the time. What this looks like in practice is a diff (similar to a redline) shown within a version control application. For example:


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(The text in these examples is from the Wikipedia article on the diff utility.)

Tower, SourceTree, and similar apps also usually offer basic editing tools: for example, you can revert selected changes if you change your mind, or push only some changes to your source code repository and worry about other changes later.

The working processes that these applications enable in software development are very different from typical working processes in legal services. Comparisons aren’t exchanged as separate files, because everyone (rightly) expects everyone else to be able to generate diffs on their own. Comparisons generally aren’t even created as separate files (again and again and again, as a document changes). There’s never a brief moment of panic when you forget to turn on track changes in Word before you start editing a document, because track changes isn’t necessary. You might not even use Word to make certain changes because you can make basic changes using the controls in a version control application.

These kinds of working processes, while routine for software developers, aren’t readily available to lawyers. Document management systems used by lawyers (the rough opposite number of version control applications used by software developers) typically (and maybe universally) don’t work this way. Some popular document management systems offer ways to create a comparison file using third-party comparison software, but this isn’t the same as clicking the current version of a document and instantly seeing how it’s different from the last version of the document (along with tools to manage differences).

However, there are a few Mac apps—intended for software development, but applicable to legal documents—that can get you some of the benefits of a software development working process.

(In all of the screenshots below, I’ve made adjustments to app preferences, mainly to the font used to show text. In other words, these screenshots don’t necessarily show what you get out of the box with these apps, but rather what you can get after some minor tinkering.)


Kaleidoscope by Black Pixel is a Mac app that’s dedicated to comparison—not only of text files (RTF, DOC, DOCX, and more), but also image files and the contents of folders. Comparing documents with Kaleidoscope couldn’t be easier: dragging the files that you want to compare to Kaleidoscope’s icon in the dock is enough to get started.

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Kaleidoscope also offers ways to search the documents you’re comparing, as well as a simple way to switch among several documents that you want to compare.

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The next two applications include features that are aimed at text comparison, not document comparison. This means that to use these applications for legal documents (which are usually DOCX or PDF files, not text files), it’s necessary to copy and paste text from a document to these applications.


BBEdit by Bare Bones Software is an extremely feature-rich text editor for professional software development, but you can use the vast majority of BBEdit’s features (including text comparison) for free. To compare the kind of text that you’ll likely want to compare in legal services, you need to create two new text files, and then copy and paste the text you want to compare into these files (you don’t need to actually save these files anywhere, you just need to create them in BBEdit). After that, comparing files takes only a few clicks.

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Atom With Split-Diff

Atom by GitHub is another feature-rich text editor for professional software development (and it’s free). One of the most interesting things about Atom is that it’s “hackable,” which means that third-party developers can add features to it by creating packages (conceptually similar to an add-in for a Microsoft Office app). One package, split-diff, lets you see differences in text that you paste in documents side by side:

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This is especially useful if you’re making changes to a portion of a larger document. You don’t need to compare entire documents; rather, you can just copy and paste the text that you actually care about.

None of these apps offer a way to save a comparison as a separate file, and in all of these apps, your document looks very different from how it looks when you’re using a word processor. But that’s really the point: these apps offer quick, simple, and (in some cases) free ways to see changes to text—not run a redline or run a backline or make sure everything is in track changes, but see changes to text. And this, generally, is all you need to do.

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