Looking cross-comment I think you're advocating for micro-payments or micro-proof-of-burn. This is better than having every user compute their own PoW as they'd

Looking cross-comment I think you're advocating for micro-payments or micro-proof-of-burn. This is better than having every user compute their own PoW as they'd purchase a small amount of cryptocurrency from an ASIC farm, which should be cheaper/faster/more efficient than using their local hardware. I mostly agree with the concept, but I don't think any such API exists yet with enough adoption to consider this a real option any time soon. Right now, if I was to ask my users to do a proof of burn for $0.0001 of BTC most of them would just close my site as they don't have any BTC. The process of setting up an account on an exchange, waiting several hours/days for KYC checks to clear, adding a credit card, buying BTC, sending it to a browser extension, and then trying the signup again is a *significant* initial hurdle. If we were in a world where I could assume all my users already owned BTC, that's a different story, but we haven't seen adoption of cryptocurrency anywhere near that level. I don't expect PoW schemes to drive that adoption either, so this seems like a poor solution today. Do you happen to know if a hCaptcha/mCaptcha-like micro-proof-of-burn tool exists already? I'd be happy to be proven wrong. That brings us back to options that exist today, which includes every user computing their own PoW. Looking at mCaptcha some more, it uses a SHA256 derivative so it's compute-hard and vulnerable to GPUs/ASICs. The author mentions some of those concerns in an earlier thread [1]. I wonder if a different proof-of-work algorithm would be better, like a memory-hard PoW, proof-of-space, and/or proof-of-wait. I'm skeptical of those too, unfortunately. [1] https://news.ycombinator.com/item?id=32341446 https://news.ycombinator.com/item?id=32341446