I would use JavaScript solution.
var macro;
macro ="CODE:";
macro +="URL GOTO=https://www.jsonurl.com"+"\n";
macro +="TAG POS=1 TYPE=DIV ATTR=CLASS:what_ever_you_are_extracting EXTRACT=HTM"+"\n";
iimPlay(macro)
var text=iimGetLastExtract();
text=text.split('"id":"')[1];
text=text.split('",')[0];
text=text.trim();
alert(text);
Edit:
The command
TAG POS=1 TYPE=HTML ATTR=CLASS:* EXTRACT=HTM
Extracts everything on the page.