Square announced today that it has closed a Series D round of funding from Citi Ventures, Rizvi Traverse Management, and Starbucks Coffee Company.

The company said in its announcement:

One year ago, Square had approximately 150 employees and processed over $1 billion in payments on an annualized basis. Today, Square has over 400 employees and is processing over $8 billion in payments on an annualized basis.

Square’s growing revenue and workforce precedes the company’s plans for international expansion later this year.

Last month, Square announced that Starbucks had signed up for Square, but also that the company would invest $25 million in Square. Additionally, Starbucks Chairman, President and CEO, Howard Schultz, joined the company’s board. More on the Starbucks deal here.

Square also recently announced a flat monthly fee for small businesses, who can pay $275 a month with 0% processing fees and no additional costs or contracts.