MacigaCSG have only .PLY Export, but you can
import .PLY in Blender and also 3DCoat


For .OBJ Export you could try the free Version
of "Womp 3D" this is also a SDF-Modeler (online Tool)

as a newest Feature (still experimental) it have also
.OBJ import and even .Blend Files from Blender

and ! very unique it have a Text Tool

Here the Link
https://womp.com/index