Although you can probably find programs that could perform json to csv conversion for you, the easiest way would be just google a bit and se one of the dozens or so websites that offer this conversion right inside web browser with a simple copy and paste method, no need to install any software.
One of such online converters can be for example found at Code Beauty, or at JSON Formatter and all can be used to convert, format, beautify, mimic or compact json files.
However, it may not be perfect in all cases, especially if there are some kind of uncommon object that not all interpreters may handle flawlessly.