OPENJSON - The easiest way to import JSON text into table

You don't need to parse JSON in application layer, you don't need to pass properties as SQL parameters, there is no risk of SQL injection attacks if you have valid JSON

I'm curious here on how you would verify that you have valid json. I can't seem to find any documentation to back up this statement or to verify the ISJSON() method is sql injection protected. So is this method really the safest? Because this makes it sound like you would have to use the application layer to verify the json is valid somehow.