Photo filter apps like Hipstamatic and CameraBag may have come first, but none of them found rapid growth as Instragram has.
Former Google employee Kevin Systrom and ex-Meebo engineer Mike Krieger founded it as a way for people to contribute media in an open and transparent environment. When it launched in early October, the startup had a measly 80 users, but eight weeks later, more than 1 million users seem to agree that the free iPhone app is a fast, easy way to apply hip photo filters to even the worst smartphone pics, transform them, and share them via social networks like Facebook, Twitter, and Foursquare. Investors also believe in Instagram's potential -- its first round of funding from investors, allegedly led by Sequoia Capital, could put Instagram's valuation at around $20 million.
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