@pixelfed It's a very basic link shortener that will work with every pixelfed instance
Basically how it works is each instance is assigned an ID when the admin enables the feature, and then using a clever namespace syntax and base encoding, instances can generate links without having to send them to the px.lfed.co domain - and the px.lfed.co service simply decodes the syntax to the proper pixelfed url using the id of the instance!