Starting jFed on OS X

On OS X, you need two things to run jFed succesfully:

Installing the Java 8 JRE

You need to have a recent version of Java 8 JRE installed on your Mac. You can verify which version is currently installed on


Verified Java JRE 8 installation

If your computer fails the verification, you can download the most recent Java 8 JRE from, as shown in the screenshots below.


Changing OS X Security Settings (needed for Firefox, not for Safari)

By default, OS X does not allow applications outside of the App Store (such as jFed) to run. This causes the error "jfed-exerimenter.jnlp" can't be opened because it is from an unidentified developer. to appear.


You can change this setting by following these steps:

  1. Open System Preferences
  1. Open Security & Privacy
  1. Unlock your settings by clicking on the lock in the bottom-left corner
  2. Change Allow apps downloaded from: to Anywhere
  1. Click Allow from anywhere in the confirmation popup

Changing Safari Security Setting (Safari only)

By default, Safari sandboxes Java applications and doesn’t give them permission to access the filesystem. This causes jFed to fail, as it needs disk access to access your user certificate.


When you encounter problems starting jFed, you can explicitly allow filesystem access by following these steps:

  1. Open Safari’s Preferences
  1. Go to the tab Security and open Manage Website Settings..
  1. Change the setting for from Allow to Run in Unsafe Mode`.
  1. Click Trust in the confirmation popup