As a long time Sublime Text[1] user, I've been using Sublime Merge[2] since the day it's been launched and it brings me the same speed and minimalism I get with Sublime Text and has evolved quite a lot to be able to do most things I need in a merge tool.

Not affiliated with them in any way by the way.

[1] https://www.sublimetext.com/ [2] https://www.sublimemerge.com/

Another fan of Beyond Compare here, but I want to point out something everyone else has missed so far, which is that BC is great for comparing all sorts of files, not just code.

For example, I use its "Table Compare" feature to compare log files from different machines, sorted by timestamp. This lets me easily see the order of operations in a distributed system.

I've been using Meld since years ago, and it's my default go-to diff viewer. The visual style they implemented helps me a lot to reason about how lines have been added or deleted from documents in the side by side comparison. Very neat!

The directory contents tree diff is also really useful.

I wish they made it even easier the basic case of comparing aribtrary text. Maybe it should be the default mode after opening the program, instead of having to click on a couple buttons, because I use it a lot to manually paste pieces of text. For example, logs from a server during testing, to compare what went different between runs.

Another welcomed addition would be "ignore masks". Some kind of regex input that could be used to quickly tell Meld which parts of the text to skip comparing. That way, comparison of log files could be made where a timestamps column would be ignored.

IMHO, Meld is the second best open source tool for doing this.

On Windows, WinMerge[1] is a better alternative. Too bad is Windows only.

For a non-FOSS and cross platform solution I recommend BeyondCompare (U$30.00)[2]. It replicates most of WinMerge UI.

[1] https://winmerge.org/

[2] https://scootersoftware.com/

Meld might be useful for comparison, but in my opinion it is inconvenient as a git merge tool. For git merge I need four panels: original file, version A, version B, merged result. Meld has only three panels.

Currently I am using KDiff3. It is a little buggy and doesn't have a nice UI but it is the best open source merging tool that I am aware of. It allows choosing lines from original file, from A, B and manual editing.

I noticed that certain popular and highly praised commercial IDE also provides only 3-panel interface for merging. This makes resolving conflicts more difficult and prone to errors.

Since everyone else is mentioning other tools, here’s my mention for vimdiff. I think I have meld installed but rarely use it because vimdiff is usually enough. As a bonus I get to use my usual editing keys when working with it.

If you want to use it with git:

    git config --global diff.tool meld
    git config --global --add difftool.prompt false

And use git difftool instead of git diff

  $ meld .

For visualization I really like kdiff3.

Or on terminals https://github.com/mookid/diffr with specific settings that use 256 colors for highlighting word differences as well.

But for manual merging I haven't found anything better than ediff. That's the only reason I install emacs on my work machines. Seemless integration into a text editor is just unbeatable.

My .gitconfig for using meld at the git merge tool:

  [alias]
    mt = mergetool

  [merge]
    tool = mymeld
    conflictstyle = diff3
  
  [mergetool "mymeld"]
    # Gives you meld, with three comparison tabs. Assuming you're merging others changes into
    # your branch, this shows you:
    # - 1st tab: yours|merged result|theirs (do the merge here into the middle pane)
    # - 2nd tab: base vs your changes (look at just your changes)
    # - 3rd tab: base vs their changes (look at just their changes)
    cmd = meld $LOCAL $BASE $REMOTE --output $MERGED --diff $BASE $LOCAL --diff $BASE $REMOTE --auto-merge

BeyondCompare is much better and available on macOS too.

> On OS X, Meld is not yet officially supported. For pre-built binaries, these OS X builds are the best option.

> You can also get Meld from MacPorts, Fink or Brew; none of these methods are supported.

Can anyone recommend any of these unsupported options? The best diff GUI tool I've been able to find for OSX is DiffMerge (https://sourcegear.com/diffmerge/) on the App Store, and I'd like to have a tree view for folder comparisons.

Maybe strange question; but which diff and merge tools are not targeted at developers?

Edit: what->which

It's not open source, and comes with all the baggage of perforce, but p4merge and p4diff are just excellent tools that I install on every machine I work on.

https://discourse.gnome.org/tag/meld ## forum

https://gitlab.gnome.org/GNOME/meld ## code

Meld 3.21.1 — 07 Jan 2022 -- thanks Meld !!

Am I the only person who opens the whole conflicted project in VSCode and project-wide searches for ">>>>>>"

I try a few times, and always I get back to kdiff3. I feel less confuse with the 3 way view and separated merge output view.

I use meld by default. Honestly it's not great. I kind of miss beyondcompare. It is however readily available and works well enough.

I use vimdiff and occasionally kdiff3 for git merging. what I really like meld for is merging two directory trees (e.g. reconciling two forks of the same code), they have the best tree diff ux of any of the common tools I've tried.

I’ve been an Araxis Merge man my whole career. Most of my peers are either Araxis or Beyond Compare.

It’d be a great if an OSS tool was as good or better. But my experience thus far is that Araxis/BC3 are simply much better.

I was given a fresh copy of Windows at work the other week and had to install all tooling afresh. I decided to take the opportunity to try meld.

The first merge I did, even after reading the website, I couldn't fathom it. I understood the paradigm of merging into $BASE but couldn't figure out how to simply take these 5 lines from $REMOTE and these 3 from $LOCAL, so went back to the trusty Beyond Compare.

Might give it another shot.

I'm an xxdiff man myself: https://furius.ca/xxdiff/

I don't like the whole "balloons with tails" thing meld does. xxdiff strikes the best balance between "being a graphical tool" and "not having distracting clutter" in my opinion.

Is Meld aware of the programming language when it does diffs? The problem I have with many diff tools is that they'll detect block moves without regard for things like method boundaries. Instead of showing the change as moving a method's ordering, with some changes within those methods, most diff tools treat it as just text moves and changes.

So to me, "targeted at developers" should mean something more than what Meld seems to offer (i.e., more than just syntax highlighting and regex filtering).

It's disappointing that programming language-sensitivity isn't more common. [I developed a Visual Basic compare/merge app in the early 90s that did a good job of this because it did extra work to understand the structure of the code, splitting methods and sorting them before comparing.]

I have used Meld very happily for years on various Linuxes. But am not a developer—use it mainly for sync conflicts on things like to-do lists and article drafts. Thank you builders! It is an awesome tool.

It's my favorite and default diff viewer.

I remember at one point there was a new version (based on gtk3 perhaps) that didn't work as well (useless type of scrollbars and slow) and I did some shenanigans to have an older version again on archlinux. However now even fresh installs do look and work good, I'm not sure what happened to that new version, maybe they improved the gtk3 based one to be as good as the one before it and I don't notice the difference anymore...

Sorry, Meld is nice, but if you use version control you are handicapped if not using a 3 way diff program.

I never found one with features good enough to make me change from Kdiff3.

I setup Git to use Perforce’s P4Merge as the Git mergetool. P4Merge is cross-platform and free and quite good.

I actually don't understand what people love about BC. The only thing I find it extremely useful for is the occasional files where inline diffs are practically mandatory, like CSVs. Other than that, I generally find it frustrating compared to TortoiseGitMerge, except perhaps for some very specific/unusual scenarios. In particular the line highlighting is annoying - instead of coloring the lines that were added vs. removed differently, it colors lines according to whether they're an "important difference" or "unimportant difference" (?!), which is borderline useless to me. What do people love about it so much?

winmerge is definitely the best windows-only open source app I've used. surprised it's never been ported to linux.

WinMerge for comparing two individual files. BeyondCompare for comparing deep nested directory structures.

Do you think the pro version of BeyondCompare is worth it compared to the standard one?

My .gitconfig for using meld at the git merge tool - which gives you that:

  [alias]
    mt = mergetool

  [merge]
    tool = mymeld
    conflictstyle = diff3
  
  [mergetool "mymeld"]
    # Gives you meld, with three comparison tabs. Assuming you're merging others changes into
    # your branch, this shows you:
    # - 1st tab: yours|merged result|theirs (do the merge here into the middle pane)
    # - 2nd tab: base vs your changes (look at just your changes)
    # - 3rd tab: base vs their changes (look at just their changes)
    cmd = meld $LOCAL $BASE $REMOTE --output $MERGED --diff $BASE $LOCAL --diff $BASE $REMOTE --auto-merge

> original file, version A, version B, merged result

Isn't one of version A or B the original file? What am I missing?

I really wish kdiff3 would get a modern update.

I agree 100% on the utility of a 4 panel diff, but I'd be careful using kdiff3... I also used it for quite a while but found that it would "auto resolve" some merge conflicts which git would flag, and I found it would sometimes auto resolve them wrong (maybe about 10-20% of the time?), and I couldn't figure out how to turn this feature off... I'm using tortoise git merge now (which also does do some auto resolve but only simpler resolutions)

i've used kdiff3 for some hairy merges with good results.

back in the days when i was responsible for regular merges for a pretty big project (weekly or so, 10-30 devs on both sides, n*1e7 LoC), i took the time to learn ediff and did my merges in lucid/xemacs.

i had colleagues at the time who had nice things to say about beyondcompare.

more recently i have seen this meld thing and it has piqued my curiosity.

favorite tool for quick no-frills out-of-practice-with-real-tools visual diff is fldiff built on fltk.

Another vote from here. I've tried a good number of merge tools but always go back to KDiff3. It has the best automatic merge conflict resolver I've seen, and really just enables me to fix things and continue.

I often have colleagues who are inexplicably afraid of merge conflicts and try to negotiate who's working on which parts of the app. I think a proper merge tool could help them to overcome this.