I will be very sad if those SHA256 hashes aren't connected to a mining backend!

Had considered building something similar, but using Cryptonite instead of SHA-256.

The problem is that the target customers are "content creator" website owners convinced that only reCAPTCHA stands between them and zombie hordes pouring out of their screens.

These people are truly "low information" decision-makers who wouldn't be puzzled if you billed them for sacrificing a goat to solve a DNS problems.

The best strategy would be a profit-sharing arrangement with cheap website designers.