I wrote my own a decade ago and since then modified it over time to fit whatever my actual needs are. For most of my needs it’s much better then any of the shelf tool but on the other side, TexturePacker has features I’ll never be able to implement as it’s just to much work and I’d be a fool to try doing so when there’s a cheap solution available already.
I’d expect there are many free tools available, a very quick google search found f.i. this one
or this