Safari 13 will be released soon; it will be bundled with MacOS 10.15 Catalina next month, and available via software update on older versions of MacOS. Safari 13 brings changes in the way that extensions work, and these changes will mean that our own Safari extension will no longer work.
We are working on a new extension that will be built to work with MacOS 10.15 and beyond, but due to the scope of the changes required in order to support new versions of Safari, it is unclear when our new extension will be ready for release. In the interim, if you find yourself without a working LinkLocker extension on Safari 13, we recommend using our bookmarklet instead. It works just as well as the extension, but without directly tying into the browser's UI.