[nyanpasu64]

kdiff3 does have a modern version: https://invent.kde.org/sdk/kdiff3/.

Unfortunately versions starting at 1.9.0 are drastically buggier than 1.8.5: Ctrl+C being incorrectly enabled and disabled (https://bugs.kde.org/show_bug.cgi?id=444636), merge errors (https://bugs.kde.org/show_bug.cgi?id=437570, fixed), drastic slowdown when loading CRLF files (https://bugs.kde.org/show_bug.cgi?id=450411, fixed), recurring assertion errors (didn't personally encounter, but https://bugs.kde.org/show_bug.cgi?id=426301, https://bugs.kde.org/show_bug.cgi?id=442618), large chunks of Git history producing unusable binaries that corrupt memory or print assertion errors when loading files, etc. I stopped following KDiff3 development and decided to pin 1.8.5 on my system, which actually works.

Another fork of KDiff3 is https://github.com/michaelxzhang/kdiff3. I haven't tested it, but I hope the alternative diff coloration makes it easier to see single-word/space insertions and deletions within a line (which is something I often fail to notice in mainline KDiff3).