It’s a software made by someone named hidefuku and the license is GPL3. It’s not something you would use for traditional frame-by-frame 2D animation but instead something more After Effects-like where you import a .psd file and use various tools like standard translation/rotation/scale keys, freeform deformation, bone deformation, z
-order, opacity and image swapping all using keyframes. There are also lots easing options although the default is linear interpolation. (whyyyy :p)
It reminds me of things like After Effects, Flash, Live2D and Spriter and overall a pretty cool program, check it out for sure if you’re interested in 2D mesh deformation style animation.