Coinhives website does result in an immediate and hard to miss increase in CPU utilization. Torrent Freak said they were told the miner was being tested for 2. In the meantime, users on the Pirate Bays subreddit were not happy, with several users complaining that the site never informed users the miner was running, let alone asked permission. Using a file sharing website was never going to be a risk free endeavor, though users could disable the miner with a plugin like No. Script or Script. Block or by adding Coinhive to an ad blockers blacklist. Embedding bitcoin mining scripts into a website is not exactly new, though the secret addition of Coinhive to one of the worlds most popular file sharing websites is throwing up red flags. As noted by Beta. News, Coinhives own documentation advises The miner itself does not come with a UI its your responsibility to tell your users whats going on and to provide stats on mined hashes. While its possible to run the miner without informing your users, we strongly advise against it. You know this. Long term goodwill of your users is much more important than any short term profits. Malware which siphons unsuspecting users CPUs for spare cycles to mine cryptocurrency is a common problem, though peaked years ago in 2. Quartz. The amount of processing power it takes to mine Bitcoin has risen 7. However, with the ongoing explosion in initial coin offerings and new crypto variants, there might still be opportunities to cash in with methods that have stopped working with older cryptocurrencies.