You don't need to use link shorteners on Mastodon. All links count as 23 characters towards your posts's maximum size, no matter how long the link really is.
By avoiding link shorteners, you are also protecting people's privacy and reducing the risk of link rot.
(There is a bug on the official iPhone/iPad app that means links are counted as their true length instead of 23, which is yet another reason to switch to a third party app such as Ice Cubes or Mona or Ivory.)
