The fact that we have no server is also the reason why there is no need to signup or provide any personal information like your email address when using SubToMe.
Adding the Button to your site
If you have a button on your site, no code is ever executed until someone clicks on it. The code executed then loads and iframe. We consider it to be very safe, but please, check by yourself: our whole code is open source for anyone to review and improve.
Registering on behalf of your users
If your application is able to consume feeds, you may want to register it on behalf of your users. This is a completely safe mechanism, but it also means anyone could register with any information. This may lead to conflicting registrations for a given name. Our policy is to only keep the latest registration for any given service name. This will favor the most popular service for a given user. It is recommanded that you use unique identifiable names in your registration, such as your domain name.