Online license activation


Diffblue Cover requires a remote license check with the Diffblue licensing server each time it is used. Offline license activation is available with the Enterprise Edition offline option only.

To perform the license check Diffblue Cover needs an active internet connection to the following servers:



The license check uses this connection to identify individual devices. Further details regarding the exact data exchanged are available in the Privacy Notice.

Activate a license

Follow these steps to activate a license. Note that:

  • Cover Plugin Community Edition is free to use but does require product verification to activate your perpetual license.

  • These steps cover online license activation only.

  • Offline licensing for Cover CLI is available for Diffblue Cover Enterprise Edition only - see Editions and Offline license activation.

Once you install Cover Plugin for IntelliJ, you'll be prompted for your license key to activate the plugin (or go to Diffblue > Activate License in IntelliJ at any time).

Diffblue Cover requires a remote license check with the Diffblue licensing server each time it's used. For help troubleshooting license keys, network connections, and proxy server settings, see Online license activation.

To check your current license details, go to Diffblue > View License Information in IntelliJ.

Configuring a proxy server

Please ensure you have the Proxy Server details configured in the IntelliJ settings page and then restart IntelliJ:

  • Windows and Linux: File > Settings > Appearance and Behavior > System Settings > HTTP Proxy

  • macOS: IntelliJ IDEA > Preferences > Appearance and Behavior > System Settings > HTTP Proxy

Please see the HTTPS certificate errors information below.

Troubleshooting license server connections

  1. Check you have an active internet connection at all times when using Diffblue Cover.

  2. Ensure you can access via a web browser; you will automatically receive a confirmation message when this is successful.

  3. Ensure you can access via a web browser, you should see the message "Welcome to the LicenseSpring API".

  4. Ensure that any Proxy Server settings are correctly set up (see the bottom of this page).

  5. Please speak to your network manager about allowing access to the URLs above, and checking that port 443 is open.

  6. For Cover Plugin, restart IntelliJ.

  7. Try temporarily disabling anti-virus, malware detector or any firewall software.

  8. A detailed logfile is available which shows further diagnostic information about the license check process - please review the logs (Cover Plugin Log Files, Cover CLI Log Files).

For further help troubleshooting licensing network connection issues, please contact Diffblue Support.

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