About the json format :)

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!