You can define custom parameters and UTM for each short link. These custom parameters will be added automatically to the long link. For example if you shorten https://linktrak.me/ and you set utm_source = email when a user clicks on the short link, the final url will become https://linktrak.me/?utm_source=email
Example: https://lktk.me/example-utm will rediret to https://thatwebsiteis.me/?utm_source=linktrak.me&utm_medium=redirect&utm_campaign=example_redirect&utm_term=linktrakme&utm_content=example_rediect_url