Your JSON input should contain an array of objects consistings of name/value pairs. It can also be a single object of name/value pairs or a single object with a single property with an array of name/value pairs. It can also be in JSONLines/MongoDb format with each JSON record on separate lines.
JSON to CSV will convert an array of objects into a table. By default , nested arrays or objects will simply be stringified and copied as is in each cell.
A Comma Separated Values (CSV) file is a plain text file that contains a list of data. These files are often used for exchanging data between different applications. For example, databases and contact managers often support CSV files.
These files may sometimes be called Character Separated Values or Comma Delimited files. They mostly use the comma character to separate (or delimit) data, but sometimes use other characters, like semicolons. The idea is that you can export complex data from one application to a CSV file, and then import the data in that CSV file into another application.