I wanted to send "*files*" from NS file Cabinet via post method body of an external api . How can I pass file or file obj to an json payload ? . Could anyone help me or provide required links to my case . Thanks in advance

I'd imagine you'd get the file contents and potentially base64 encode it.

There is an extension for vscode called Netsuite Upload. It uses a RESTlet to upload and download files from the file cabinet. You can grab the code that does the upload and create your own RESTlet.