How can I track UTMs in my optin form?

Though this is a very broad question, let's try to answer here. UTMSimple is the simplest and greatest tool that allows tracking UTMs and other trackable data...

As soon as UTMSimple is activated, script will detect all the UTM related fields in your optin form and autofill them approproately wihout you doing anyting (hence it is THE simplest :) )