Text document created by NJStar, a word processor used for authoring Chinese, Japanese, and Korean documents; supports non-English character sets as well as instant translation between English and Chinese, Japanese, and Korean languages. What is an NJX file? The NJX file type is primarily associated with NJStar Document. A file extension is the characters after the last dot in a file name. The easiest way to open NJX files is to try downloading some of the most popular software that uses NJX extension. How to open NJX files. NJX file? We collect information about file formats and can explain what NJX files are.