You can export the country list to your developer console. You can open the developer console in Google chrome with the shortcut:
| Command + Option + J | Control + Shift + J |
| Mac | Windows / Linux |
|---|
Then click on the Export Field to show the countries as string in the console. You can copy and past this to an other Geolizr instance.
Here a screencast for export:
and here a screencast for import: