Not the OP, but just another data point. While it's interesting that you're thinking outside the box on pricing models, I would personally never signup for a l

Not the OP, but just another data point. While it's interesting that you're thinking outside the box on pricing models, I would personally never signup for a login service on a revenue sharing basis - I'd much prefer a monthly fee (the standard SaaS model). The percentage also seems way to high in comparison to the value-add - Stripe, who actually process the payment, are taking less than you. Having said that, I don't think I (or most of HN) would be the target market for this kind of login service. But I wonder if you can find some kind of niche. Something for individuals and micro businesses that have no tech chops and just want an easy way to sell stuff. For that though, you'd need to go further than login, perhaps turning it into a WordPress plugin (or for another platform), and doing something to provide sales through Stripe, so the user doesn't have to build that themselves.