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.

Web Start applications are regular Java applications that are written to the JNLP specification; but there are differences you'll want to know before you head down the JNLP path.

Java Web Start simplifies deployment of applications, but Sun's Plug-in makes the task even easier. See how the Java Plug-in from Sun enables browsers to fetch a Java Virtual Machine (JVM).