JSON is back-end?
JSON-LD is one of the tool Google use to create Rich snippets for website that will show up on Search results. The best thing about this? It is very easy to use and requires little effort from the developer. But s/he has to think the page content thoroughly.
Content Management Script?
Tagging the content of a page with JSON-LD is also incredibly practical because it can be done for an already existing page. Google provides a mark-up helper for structured data where anyone can tag the content of a page live on an active url.