As a developer on PL/JSON I would not recommend another plsql implementation of JSON.

But if you're using modplsql to Apache, I recommend JSONView for firefox. It's a really nice product that prettyprints json in your browser. All it requires, is the correct mime-type: 'application/json' to be set (it even displays lists/arrays correct).

That's >>OWA_UTIL.MIME_HEADER('application/json', true, 'utf-8');<< before printing with htp.print i plsql.