A JSON File is a file containing JSON object and JSON Array. The JSON file is mainly used for exchange data from the server to web Application or Mobile Application.
it is a stander Data exchange format. JSON files are very lightweight, text-based, human-readable, easily editable with any text editor.
You can refer other below awesome post of JSON.
Refer Below Powerful and easy Tools for JSON Data.
You can refer below post for JSON format example.