When comparing Meld vs WinMerge, the Slant community recommends Meld for most people. In the question“What are the best folder/file compare/diff tools for either OSX, Linux or Windows?” Meld is ranked 1st while WinMerge is ranked 6th. The most important reason people chose Meld is:
In addition to comparing two files it also allows you to edit them right in place. What's more, the diffs are updated automatically.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Supports editing files directly
In addition to comparing two files it also allows you to edit them right in place. What's more, the diffs are updated automatically.
Pro Free and open source
Meld is freely available on Linux, Windows and OSX (through MacPorts, Fink or Brew).
It's also open source and distributed under the GNU General Public License (GPL).
Pro Comparing two or more different folders is supported
Meld allows users to compare two or three different folders for differences. But if a user wants to 'zoom in' and compare files contained in these folders, Meld gives you the ability to do so and launch file comparisons between files contained in different folders or in the same folder.
Pro Supports some simple version control actions
Meld supports the major version control systems (Git, Mercurial, Subversion and Bazaar). You can launch file comparisons between different versions to see what parts changed before commiting.
Simple version control actions are also supported and possible. For example: commit/update/add/remove/delete files.
Pro Three way comparisons
You can compare up to three different files for differences. Plus you can edit files from the comparison view and the diff will automatically update.
Pro Simple GUI
Pro Easy to use and visually appealing
Stragihtforward and you don't need to read tutorials to use it. Just click and select and you instantly see how the difference and merges are connected to eachother.
3 sub- windows, instead of 4, which reduces the mess during merge and let you see more of the surrounding files rather than just 5 lines.
Pro Fast on Linux
Relatively fast on Linux.
Pro Internationalization
Through the GNOME Translation project and the translators that have worked for it, Meld is available in multiple languages. You can check if your language is supported in the translation statistics page.
If you can't find your language or if your language translation is unfinished and you want to help, you can do so by joining the GNOME Translation Project.
Pro File edition
You can quickly copy changed lines (or files in folder comparison) in both directions with keyboard shortcuts. You can edit the files as well, with syntax highlighting of some languages.
Pro Compare folders and files
Can show what files has been changed in a folder, allows comparing files in tabs.
Pro In line comparison
Can show differences within a line.
Pro Free & Open source
Winmerge is a free and open source tool.
Pro Good shell integration
Select two files and compare them. Alternatively, select one file, navigate elsewhere, select the other file to compare.
Also supports drag'n'drop of files / folders from Explorer.
History of past comparisons.
Pro Lightweight, quick startup
Binary is less than 3 MB, so it starts quickly
Pro Filters
Can filter out files for folder comparison, lines for file comparisons, with regular expressions.
Options also allow to ignore whitespace differences, white lines, case change, line-ending changes, etc.
Pro Good navigation
Keyboard shortcuts (and toolbar buttons) to navigate to next (previous) difference, side panel shows a map of the files with changed lines and allows to jump to a given place.
Pro Good detection of moved lines
Detects when a block of lines has been moved in the file and shows the relation.
Cons
Con Slow on large files
While larger files are supported, they can take a long time to load. (20,000 lines+)
Con Program opens slow on Windows
Update: This issue should be fixed on Meld-3.18.1-win32.msi released on 27 May 2018. See http://meldmerge.org/news.html
Con Very slow mac OS port
Con No option to compare individual rows horizontally
Unlike other options, like Beyond Compare, Meld has no option to compare individual rows horizontally.
Con Not having a base value to reference can make merging less certain
Con No Explorer context menu integration
In Windows, there is no option to right-click and compare files easily.
Con No official OSX Support
Some attempts have been made to port, but nothing easy or fully working.
Con Missing contextual command line options
Not all contextual elements are exposed to the cli. Specifically the ability to follow our not follow symlinks, but also things like file system metadata parsing. These options and others can only be toggled via the gui's settings window.
Con Windows only
It's only available for Windows. No Mac or Linux versions available. It is possible to run in Linux via WINE, although a bit unstable.
Con Development is spotty
The latest version (2.16.0) was released in November 2018. Before that the last official release was made in 2013. The 2.16.0 is actually one of the two forks (Winmerge-v2-jp) that were kept maintained throughout the years, it just got named as the official release.
The other fork, WinMerge2011 is still being actively developed too. It's on par with the historical version, and has additional features such as showing only differences and a 64-bit version.
An 'official' list of forks is maintained here.
Con No 3-way merge
Cannot merge 3 files, can do only comparisons by pairs.
Makes it unsuitable for merging operations, still useful to compare two versions in the history.