Multiple options, but any bot detection can be bypassed, if you offer free GPUs you'll run into serious motivated people. Only accept professional emails(i.e n

Multiple options, but any bot detection can be bypassed, if you offer free GPUs you'll run into serious motivated people. Only accept professional emails(i.e name@company.com) from a domain that is older than X days, you can find APIs to find out if a mail is from free providers. + maybe a phone number from the same country of their IPs. "Sign in with google" is pretty useless, you can bypass that for pennies. If you're going to require a credit card, you can probably filter them to block debit/prepaid card, or try to make a temporary charge for a few dollars before reverting it. You can use websites like https://seon.io/ https://seon.io/ to find out if a mail/phone number looks legit, they check things like if they actually used it somewhere else etc... How much GPUs time are you going to offer for free? The question you really want to answer, is how do I make registering a fake account more expensive that whatever someone would get from mining crypto with your GPUs. You can and should of course should block proxys/vpn ips. Some basic bot protection would not hurt, but it's not an actual solution. If you don't expect a huge amount of free users at first, you could maybe check registrations manually. Maybe ask them to sign in with linkedin and check their account legitimacy(number of relations etc...) An actually viable solution would probably be a mix of multiple of these things, your goal is to make it expensive to register more than one account, not impossible.