Social network giant Facebook announced Monday that it will buy San Francisco-based Instagram — an application that allows users to doctor cell phone photos and share them with friends — for $1 billion in stock and cash.

The acquisition will be Facebook’s biggest yet, the New York Times reports.

Instagram’s service is barely two years old, but already has close to 30 million users. Though the app was originally released only for iPhones, the company launched an Android version of the app last week.

Some fans of Instagram’s service are worried that it might go the way of FriendFeed, Hot Potato and Gowalla — all startups Facebook acquired and discontinued.

Mark Zuckerberg, Facebook’s founder and CEO, said they plan to keep Instagram running as a separate service for the time being.