Jed McCaleb likes building things that make powerful people nervous.

In 2000, as Napster was starting to implode, he came up with a peer-to-peer filesharing network called eDonkey 2000 that soon became the world’s most popular way of sharing music online. Six years later, following legal action from the Recording Industry Association of America, he got out of the game.

Act Two was Mt. Gox, which is now the world’s largest exchange for Bitcoin, the widely popular digital currency. McCaleb started the site in 2010, using a leftover domain name he’d registered a few years earlier for a card-trading site. He wrote new code to handle Bitcoin-to-dollar trades, and the site was an instant hit. Within a few months, customers were wiring him large amounts of cash for their trading accounts, and McCaleb decided to bail, citing a hazy regulatory market. Sure enough, the feds are now starting to crack down.

So now it’s time for Act Three: an alternative to Bitcoin known as Ripple. The project is, in some ways, an effort to hone and improve the wildly popular digital currency, hoping to move us even further into a world that isn’t so dependent on traditional money and the established organizations that control it. The only trouble is that McCaleb may once again raise the ire of the feds.