10. Coinbase

Buy, sell, HODL.

Founders: Brian Armstrong (CEO), Fred Ehrsam
Launched: 2012
Headquarters: San Francisco
$225.3 million (PitchBook)
Valuation: $1.6 billion (PitchBook)
Key technologies:
Financial services, e-commerce, investing

George Kavallines | CNBC

Coinbase, the leading U.S.-based cryptocurrency brokerage, is on a bit of a buying spree. In mid-April it bought Earn.com, a start-up that uses blockchain for its paid email service. Earlier in the month, it also purchased Cipher Browser, an app browser for blockchain. Earn's CEO Balaji Srinivasan will join Coinbase as CTO.

Read More: FULL LIST: 2018 DISRUPTOR 50

The company, which is returning to the CNBC Disruptor list after a three-year absence, has raised $225 million in funding, making it the biggest private bitcoin company out there. Among the investors: the NYSE, BBVA (a large multinational bank), along with personal investments from former Citigroup CEO Vikram Pandit and former Thomson Reuters CEO Tom Glocer.

The San Francisco-based company was started by Fred Ehrsam, a former Goldman Sachs trader, and Brian Armstrong, a former engineer at Airbnb. As a digital currency wallet and platform, Coinbase enables merchants and consumers to complete transactions using new digital currencies. Bitcoin is the most well known, but the company also facilitates the use of ethereum and litecoin. It makes money by charging users a 1 percent fee to convert dollars into and out of bitcoin. Merchants like it because the fees are less than what they pay to process most credit card transactions. Coinbase has over 20 million users and has facilitated more than $150 billion in cryptocurrency asset trading.