Hey! I've been looking at your website for so long always thinking this would be the perfect use case. Fan of your product.

Running a mint does not make you an MSB in your case. Think of it as replacing your ledger: instead of crediting users a balance when they top up and debiting their account when they make a request, you don't do that, instead you give them ecash when they top up.

When they use the service, they pay you back with the ecash. The ecash acts as an access token to the API. We've been doing this similarly to L402 but with the payment directly included in the request (as ecash). The benefit is privacy and security among other things.

Let me know if you have questions, would be happy to talk more and share ideas.