[Minor update 2020-09-06]

I use Beyond Compare a lot – every day. It’s the best “diff” utility I’ve ever found.

But I also need to compare Word documents a lot – also every day. And Beyond Compare isn’t very good at that.

Microsoft Word has it’s own “legal blackline” (sometimes called “redline”; I don’t know why) compare which works well, but is very tedious to start each time. To use it (in Office 365), you need to:

1. Open a document
2. Go Review>Compare>Compare two documents
3. Find the original document and select it
4. Find the revised document and select it (yes, even tho you already have it open)
5. Click OK

If, as is often the case with me, the two documents are in different folders, this is a lot of work.

With Beyond Compare, on the other hand, you can just select two documents in File Explorer, and right-click on “Compare”. Done.

Here’s a way to get Beyond Compare (BC) to launch Word’s legal blackline, the same easy way. Step-by-step:

1 – Download script “Diff-Word.ps1” into the BC4 folder (usually “C:\Program Files\Beyond Compare 4”)

(That file is modified from what I found at https://github.com/ForNeVeR/ExtDiff – many thanks to the author of that!!)

2 – Open Beyond Compare and do Tools>FileFormats, go to the bottom of the window that pops up and click ‘+’, then choose “External Format”.

3 – In the Mask box paste in “*.doc;*.docm;*.docx;*.dot;*.dotm;*.dotx” (without the double quotes).

4 – In the Quick Comparison paste in (again without the double quotes): “powershell -ExecutionPolicy ByPass -File Diff-Word.ps1 %1 %2”

5 – In the Compare View box paste in (again without the double quotes): “powershell -ExecutionPolicy ByPass -File Diff-Word.ps1 %2 %1” (note reverse order of parameters at the end – this is necessary)

6 – In the Description box past in (if you care): “Make Word open it’s own blackline compare.”

7 – Click Save, click Close, exit Beyond Compare.

Now to use it, the order in which you do things matters (because of the way Word’s compare works – it marks revisions against an “original”; if you do things in the wrong order you’ll be marking the original against the revised version, which isn’t the same thing).

So to use it:

1 – Right click on the ORIGINAL file and choose “Select left file for compare”.
2 – Right click on the REVISED file and choose “Compare to”.

That’s it. This will open 2 Word windows, one with the blackline change marks (revised marked against original), and the other with the revised document (no changes – ready to edit further).

If you don’t want that 2nd window (just want the changes), put a ‘#’ (comment) in front of the line that starts “$new =” in Diff-Word.ps1.