A JNLP file launches a Java Web Start app, and Windows 11 can’t open it on its own. Modern Java versions (11 and later) no longer include Java Web Start, so the easiest fix is to install the free, open-source OpenWebStart, then double-click the JNLP file, or right-click it and choose Open with > OpenWebStart javaws. If the app specifically requires Oracle Java 8, installing Java 8 also adds Java Web Start (javaws), but check Oracle’s license terms for business use.
Here’s how to set up each option, make JNLP files open automatically, and fix common errors. The same steps work on Windows 10.
Option 1: OpenWebStart (recommended)
- Download OpenWebStart for Windows from openwebstart.com and run the installer.
- Keep the option to associate .jnlp files checked during setup.
- Double-click your JNLP file. OpenWebStart downloads a compatible Java runtime automatically if needed, then launches the app.
- If Windows asks how to open the file, choose OpenWebStart javaws and click Always.
Option 2: Oracle Java 8 with Java Web Start
- Download Java 8 from Oracle’s Java download page and install it.
- Right-click the JNLP file, choose Open with > Choose another app, and pick Java(TM) Web Start Launcher. If it’s not listed, click Choose an app on your PC and browse to javaws.exe in the Java 8 bin folder under Program Files.
- Check Always and click OK.
Oracle Java 8 is free for personal use but may require a paid subscription for commercial use. If you’re at work, ask your IT team which Java to use.
Option 3: Open from Command Prompt
Open Command Prompt in the folder with the file and run javaws launch.jnlp, using your file’s name. This shows error messages that can help with troubleshooting.
How to make JNLP files open automatically
- Go to Settings > Apps > Default apps.
- In the search box, type .jnlp.
- Click the current app and choose OpenWebStart javaws or Java Web Start.
Troubleshooting
- File opens in a browser or Notepad: Set the default app as shown above. Browsers download JNLP files but can’t run them.
- “Application blocked by security settings”: The app may be unsigned or use outdated signing. With OpenWebStart, check its Settings > Security. With Java 8, open Configure Java > Security and add the site to the Exception Site List only if you trust it.
- App needs an older Java version: OpenWebStart can download the version specified in the JNLP. Some legacy apps only work with Java 8.
- Nothing happens: Run it from Command Prompt with javaws to see errors, and make sure you have the latest JNLP from the website, since some expire.
Frequently asked questions
Is it safe to open JNLP files?
Only open JNLP files from websites you trust, like your employer, bank, or a known service. They launch programs on your computer.
Can I open a JNLP file without Java?
No. JNLP files need a Java Web Start launcher. You can open them in Notepad to see the settings, but that won’t run the app.
Why did Java Web Start disappear?
Oracle removed it starting with Java 11. OpenWebStart was created to keep JNLP apps working on modern Java.
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.