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.
I didn't know it. it can load "glsl" Pixel Shader file generated from "https://stephaneginier.com/archive/editSDF/" !
From its About page : "Shadertoy is the first application to allow developers all over the globe to push pixels from code to screen using WebGL since 2009."
there are some converters on line http://codebeautify.org/jsonviewer
alas the xlm resulting can't be reloaded inside Kerkythea (the only one for the moment that I remember that reload xlm file! :)
I believe that with Processing (a free coding program, you can reload json file format with some library installed and save as obj)
but i want find more simple! :)
In any case json format is reloaded by the editSDF itself!