By going through this API documentation page, is it possible to tell which database is being used in the backend?
MySQL would require a php file on the server to handle the requests, make queries, pack data in JSON format then send it back to the device. But in this case parameters are passed to .json files. Please advice
There is no way to "see through" to what the backend service actually used to provide you with the information you may query for. Are you sure you want to continue using this product? The site notes that Zomato will no longer be available to individuals, and that your API key will be disabled if you don't use it monthly.