Other sites have used cryptocurrency mining in lieu of (or in addition to) advertising. Sometimes, it’s done surreptitiously without users’ consent — The Pirate Bay admitted to secretly adding Coinhive integration last year, and hackers have planted mining malware on other sites. In this case, it’s an opt-in program; a spokesperson tells FT that testing started on Monday.
Cryptocurrency mining scripts can negatively affect system performance, since they’re running intensive calculations as you browse the web. But they also offer a way to recoup lost ad revenue without resorting to paywalls — something that sites like The Atlantic have done for visitors who are running ad-blocking software.