There is sample code available in the API
documentation. Go to Account and click on API
/Signup Form. You will see a link to use Mustang List’s Signup form at the top of the page. Next you will see code you can use to create your own custom signup form and custom success and failure pages. At the bottom of the page, you will see some sample php code as an example of calling the API
and examining the returned value. Contact Mustang List for more complete documentation on using the APIs.