A little-hidden gem in Simplero is the ability to send add a "track" URL parameter to any URL or even to a POST request.
The value that you supply will be captured and stored in the session, and then stored with any list subscription or purchase that happens after that.
That way you can track where links are coming from in a simple and straight-forward way.
It is a secret feature because it is implemented in the most basic and simple way. It is not something we are committed to supporting or flushing out. However, it is there if you feel adventurous enough to use it.
So if you have a URL that says
you can add a track parameter after your URL link so it looks like this:
and then you will be able to see that any signups were referred from your sidebar.