I am regularly needing to convert CSV files into JSON, and to help me manually get the job done, as well as automate on a schedule or via the Postman API, I created a simple request for pulling a CSV file and converting into a JSON response, and then rendering using the Postman Visualizer.
You can view the documentation for the collection in my file format conversion public workspace. I will be adding other file format conversion requests for this collection as I need them. If you have one you’d like to add feel free to fork the collection and add it yourself! ;-) If you have any feedback, feel free to comment on the collection, or any part of requests.