Magica Voxels ---> obj ---> Moi :) http://voxel.codeplex.com/ MagicaVoxel
_Importobj by Max Smirnov
Explodemove by Michael Gibson ;) (20 150 surfaces! )
I don't remember if you have already reported this web app, but if not,
I think you'll find rather interesting these great 3d web app from Stéphane GINIER (https://stephaneginier.com/) :
But I don't know how to export in obj format. it seems that it's available only a strange "glsl" (OpenGL) format,
and I don't know how to use it in order to import the geometry data into other software.