This is a pretty cool web program, and my friend has already verified it can export and load into Unreal (and thus other apps) with ease.
http://monstermash.zone/
The website is monstermash but subtitle text introduces the software as MonsterMesh. I wonder if the latter is just a typo. Or maybe the software has the later name while the guy doing training for that software uses the former name. Seems that MonsterMash is a takeoff on the song "Monster Mash" which was supposed to be a form of dance.
https://www.youtube.com/watch?v=SOFCQ2bfmHw