It's a tool that enables you to create live demos of your widget on any website.
Assuming that you have a widget that you would like to demo on a potential customer's website, using this tool you can do that in few seconds.
Regarding the email request, we have tried to build something simple without registration. So we are asking for the email to track how many different ppl are using it. We won't share your email address with anyone and we won't send you promotional mails.