Diffuse Merge Tool: compare (and merge) text files visually


Have you ever needed to compare multiple versions of a text or code, and wished that the differences would be highlighted visually? This is exactly what this program does: Diffuse Merge Tool is a free, visual text file comparison and merge tool.

It will display text files on-screen simultaneously each in their own pane, highlight the difference, and offer easy merging options.

This program is unusual in that, aside from the typical 2-pane two way comparison, it provides a 3-pane three-way comparison as well.

It also provides syntax highlighting for a wide array of coding languages, a set of tools to identify differences and merge some or all of them, and tools to manipulate text. It can be launched from the Windows context menu (on both 32bit and 64bit Windows) for quick, on-the-fly access.

Diffuse Merge Tool is open source and multiplatform (Windows, Mac, Linux, and BSD).

Diffuse Screenshot1 - 2 wayDiffuse Screenshot2 - 3 way

You can see from the screenshot that this program will display text files side-by-side and highlight differences in red. But if you haven’t seen this type of visual comparison tool before you will certainly find the highlighting of the absent “empty space” useful. This is a neat device that keeps similar rows in a file opposite each other, such that the insertion of rows or sections in one file doesn’t cause a confusing misalignment. Otherwise, here are some PROS and a wish list.


  • Two or three way comparisons: in case you missed this detail in the introduction, Diffuse Merge Tool can compare 2 or 3 files simultaneously, which I hadn’t seen before.
  • It looks and feels good: there is something about the user experience and the way it highlights differences that is very pleasing and intuitive.
  • Nice set of tools: powerful set of both text merging tools as well as text manipulation tools
  • Syntax highlighting: which is pretty much standard for this sort of tool. Covers every conceivable coding language.

Wish list:

  • Windows context menu unintuitive: launching the tool via the context menu after selecting two (or three) files results in each of them being opened singly in their own instance, instead of being compared against each other (which is somewhat unintuitive). It would be nice if it asked upon launch or there were subentries in the context menu for comparing files against each other. Also would also be nice to be able to switch the context menu entry off in the settings.

The verdict: most readers would want to know if Diffuse holds a candle to WinMerge, which is the de-facto leader in this category, and my answer is that it certainly does. Diffuse does not quite have the same range of functions and bells and whistles as WinMerge (which is extendible via plugins), but in many ways this does not seem to matter and Diffuse is a very solid program all the same. (And, possibly, is the more user friendly of the two).

WinMerge also offers a folder comparison functionality, which Diffuse lacks, but I never thought it was a particularly inspired folder comparison tool anyway (if you want visual folder comparison use FreeFileSync). On the flip side Diffuse is unique in that it offers 3-way file comparison which I am sure many users will find extremely useful.

One last disclaimer: I may not be as qualified to give a verdict on this as, say, coders and developers who might need and/or use this function very frequently, but I do know a quality program when I see one, and this is a quality program that I recommend highly.

Version Tested:

Compatibility: multiplatform; Windows, Linux, Mac, BSD.

Go to the program home page to download the latest version (download the .win32.exe file for Windows, which is approx 6.8 megs).