When comparing Meld vs Kdiff3, 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 Kdiff3 is ranked 3rd. 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 Supports 3 way merges
For modern version control systems, 3way merge support is a basic requirement, but many other open source diff viewers do not adequately handle 3way merges.
Pro Free and open source
KDiff3 is completely free to download and use. It's also open source released under the GPL.
Pro Can compare directories
It is able to compare whole directory trees.
Pro Supports editing files directly
In addition to comparing two files it also allows you to edit the merge result right in place.
Pro Diff by character not by lines
On comparing two files, difference is shown by characters; not by lines.
Pro The UI is customizable
Allow customizing colors regardless of user/system theme.
Pro Supports manual code aligning
With selecting code in one window and hitting Ctrl+Y, then selecting some other code in second window and also hitting Ctrl+Y you can manually align the code.
Pro Preprocessing before calculating differences
There are options that may pre-process compared files before Kdiff3 actually do a comparison - to ignore for example automatically generated dates and/or revision numbers added by commit hooks.
Pro Context menu shortcut
You can right-click a folder/file and the options:
- Save <file> for later
- Compare with
will be available, making launching KDiff3 really convenient.
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 Cannot do inline diffs
Comparison of 2 files is always side-by-side and there's no option for inline views. Overall a rather poor and confusing UI in general.
Con Confusing GUI
4 sub-windows (when you really only need 3), a lot of different colors and even more confusing result-window. No links what has changed between versions and and the result. It clearly shows it's dated or rather outdated. Great if you ever need to do a command line merge, otherwise it sucks.
Con No precise editing of the compared files
Precise work line-after-line is not possible. Only a version after the automated merge-step is editable, but not the two files separately.
Con No longer supported by Homebrew for MacOS
Cannot be installed easily on Mac as of Aug 2019.
Con Problems when files have different number of lines
For example, if you add 3 lines: A, B and C locally but on the other change there are only A and C, Kdiff3 will work out that A was added, then it says that B conflicts with C but adds C again anyway.
Con Slow for large files
Con No image compare
Compare is text based.