MakeJNLP allows you to launch Java Applets using Java Web Start.

Download the file below, then drag that file to your Bookmarks bar. To use it, you need to click the bookmarklet you created twice.

Download Link

MakeJNLP has been tested with:

• Mozilla Firefox 44+
• Opera 10.63+
• SeaMonkey 1.1.19+
• Google Chrome 49+

• Incompatible with Internet Explorer and Edge.
• Recent versions of Chrome (sometimes) discard the created JNLP file after saving.
• No support for <embed> tags.
• Fix horizontal overflow.
• Can't load unpacked .class files (JWS limitation?).
• <object> parameters
• <object> get required JRE version from classid and/or codebase.

• Download Java
• Java and Chrome
• Oracle Blogs - Moving to a Plugin-Free Web
• Security level settings in the Java Control Panel
• JNLP file specifications
• Embedding applets using tags

• Java Tester
• Applet Development Examples
• Music and Computers
• Double Pendulum
• Cortado streaming applet
• Batik SVG Toolkit
• JavaPC
• Jake2

Not all of the sites listed are guaranteed to work with makejnlp, though.