It can be difficult to tell what has actually changed when running git difftool on a .kicad_pcb file because KiCad embeds timestamps into the file that change when the file is modified:

Luckly, we can tell git to use a custom difftool using the --tool=<tool> argument.

First, we need to create a custom shell script to pass to git difftool --tool=<tool>. I use Kaleidoscope.app as my git difftool on macOS, so I named this script kicad-ksdiff and put it a directory on my $PATH:

#!/bin/bash

# Run with the following command:
# git difftool --tool=kicad-ksdiff board.kicad_pcb

# From https://forum.kicad.info/t/a-better-difftool-for-kicad/40042/3
tstamp() {
  sed -E 's/([(]tstamp )[^)]*/\1-/g' "$@";
}

ksdiff <(tstamp "$1") <(tstamp "$2")

Next, we need to configure git to call this script when git difftool --tool=kicad-ksdiff is invoked. Put the following in your global .gitconfig file:

[diff]
	tool = Kaleidoscope
[difftool "kicad-ksdiff"]
	cmd = kicad-ksdiff $LOCAL $REMOTE

Now, running git difftool --tool=kicad-ksdiff <board>.kicad_pcb ignores any timestamp changes and only shows changes to the actual design:

Revision History Link to heading

Feedback Link to heading

Anything I got wrong? Have you found better ways to filter out timestamp changes?

Let me know in the comments below.