Upgrade is also using a blockchain—the digital ledger technology that underpins cryptocurrencies like bitcoin—to prevent loan-data meddling. "The fact that someone could get into the system and change the data was a big control failure," [at LendingClub] he says. Two Upgrade engineers worked for a couple of months to build an application on the Ethereum blockchain. Interactions with borrowers, such as loan-agreement signatures, get digitally inscribed as transactions on the blockchain every 10 minutes, creating an immutable record of loan data.
Source: LendingClub Ex-CEO is Staging a Comeback with New Fintech Startup (warning: Forbes, so be sure to turn on your adblocker and mute your computer volume because the ads autoplay video)
I've heard a few pitches about private blockchains that operate exclusively within a company. I don't know if Upgrade did anything truly different here that was not possible before with a relational database with strong access controls. You could just modify database table permissions so that certain tables are append-only so that data cannot be modified once it's added. Moreover, it probably wouldn't take two engineers a couple months to build.
That said, this is a cool use case and is probably one of the more impactful uses of blockchains that I've heard of in the past while.