Recently when posting links I've found Twitter has no longer offered to automatically shorten URLs; they used to be shortened to a max of 20 characters just when I pasted them into the tweet box. Now they take as many characters as the full URL.
Twitter – Why doesn’t Twitter’s URL shortening always work
twitterurl-shortening
Best Answer
It does work, they have just changed the way it is implemented. It now tries to leave URLs as you posted them so that users can easily see where the link is going rather than all links being http://t.co/xxxxx
See this help article on Twitters Link Shortening service.