How to Force Bots/Apps to use your URL Shortener

I've used several Twitter apps and they all seem to shorten URLs using the website's own URL shortener instead of bit.ly or tinyurl.com or something. For instance, Amazon's is amzn.to. Is it that these apps ar开发者_开发问答e really keeping up with the most popular sites (Amazon, Dell, ESPN, Microsoft, Google, Apple, etc) or is there a metatag, javascript, or something else that I can add to my web application to have it use a custom URL shortener? We have one that we've used forever as our domain name is over 20 characters in length.

Basically, apps that are supporting bit.ly and other URL shorteners can tell who you are and thus shorten the URL appropriately using a custom domain.