This is the simplest app type in Blink. All you need is the URL of an external Service to create a shortcut to that service from the Blink Launchpad.
Make sure that your external shortcut URLs are fully responsive. Non responsive sites significantly degrade your user experience.
External Shortcuts are effectively bookmarks that live in your launchpad for easy access.
For example, this will create a new app in the Discover Store which links users to the TFL Tube Status page - a public resource available on the internet.
Here, an external shortcut to the Tube Status page on tfl.com is created ready for publishing in the Blink Discover Store.