Since JNLP files are simply Java Web Start files that open applications through an Internet browser, any browser that works in Windows 8.1 will open a JNLP file as long as you have Java installed.

Each JNLP service has a name and a corresponding interface. Two of the most useful services are FileOpenService and FileSaveService, which allow for the reading and writing of files, respectively.

Like Java applets, your application will be constrained to a sandbox on the client unless you used signed jars and configure permissions correctly in your application's JNLP file.