Sendgrid Optin Form HTML+Javascript+API Integration

I would like a small widget developed to allow users to signup for my Sendgrid marketing campaign. The widget will need to be used on a PHP based site as well as a Django site. I would like the widget to use a pluggable style approach where I can add in to both sites. The code should have easily adjust API Key and accept a marketing list to apply signups to. The widget will be comprised of two parts; The script to send/recieve data from the sendgrid API as well as basic HTML form to collect First name, last name, Company Name. [login to view URL]