In January of this year, Foursquare published this fantastic infographic, visualising its 3,400% growth in 2010. In May of this year, Foursquare hit 9.3 million users and boasted 600 million checkins total, averaging 3 million per day from its nearly 10 million users. It’s been an exciting 2 years for New York City’s darling location-based startup. And today, it officially announces 10 million Foursquare users.

Over 400,000 businesses use Foursquare to connect with customers, and 10,000 developers build their own location-based apps using Foursquare’s API. It’s easy to forget the company only launched just over two years ago around a kitchen table in the East Village. Direct competitor Gowalla only surpassed 1 million members in February of this year – no small feat in its own right.

We’ve been waiting for the official word since we were first tipped off in early June when co-founder and CEO Dennis Crowley tweeted the following:

Screen shot 2011 06 20 at 4.36.12 PM 520x234 Milestone: Foursquare hits 10 million users

It’s quite the birthday present for co-founder and CEO Dennis Crowley, who spent his 35th birthday eating boneless buffalo wings in Chicago’s O’Hare Airport at Chili’s Bar and Grill. (He celebrated properly after arriving back in New York.)

Love the Foursquare team? Check out our interview with Crowley on where he’s the mayor and don’t miss this epic shot of co-founder Naveen Naveen Selvadurai “icing” astronaut (and recovering alcoholic) Buzz Aldrin at last year’s Webby Awards.