Natron

Powerful and open source !

The program crashes out with no good reason too often. Very unstable, at least on a Windows system.

I tried to use with a 4K monitor, Plasma 6, Wayland, but this app is written in the ancient QT 4.8, and it did not support scaling. It doesn't work with QT_SCALE_FACTOR, and there is no in-built scaling setting. There is a font size setting, and I tried setting a bigger font to make it somewhat usable, but still things like icons or drop-down buttons were too small, so I gave it up using it.

Would love it if it works, I can’t even open it I tried uninstalling and restarting it I even reset my entire computer and yet it still doesn’t work, I hope they fix it, i hope it’s not because of not having a powerful computer, cause I’m tried of upgrading

It's a pretty robust software in many respects. HOWEVER, it doesn't support sound, which is the Achilles Heel right now. You cannot sync visuals to audio without a convoluted, cumbersome work-around so if sound syncing is important, then this fails badly. But I heard they're working on sound (As of July 2022). So hopefully one day I can actually switch over to Natron. A POSITIVE for After Effects veterans is that there are several views like "Dopesheet" (which Nuke has too) which feels slightly more akin to After Effects if you're used to that, but you do have to get use to the nodal workflow first.

I sooo hope they keep this project alive and kicking! Apparently they're looking for a new project maintainer.

Seems intimidating but actually easy to use after watching a couple of basic tutorials (concepts are simple, graph is actually easier than some menu based software). A good surprise