In just two years, the social-networking photo app has grown exponentially in both value and user base, and now it might get even more investments, CNet News reported citing The Wall Street Journal.

The free iPhone photo sharing app that boasts users such as President Obama, skateboarder Tony Hawk, singer Justin Bieber, actress Zooey Deschanel, and rapper Snoop Dogg might be getting new funding that will value it at $500 million.

One year ago, Instagram was valued at just $25 million. Despite this enormous growth and a base of more than 15 million users, the popular app has struggled to make money since its inception in March 2010.

Unlike other apps and social-networking sites, Instagram isn't well positioned to feature advertising, paid content, or other e-commerce strategies since photos take up most of its screen real estate.

However, over the past year, the app raised $7 million from Benchmark Capital, Baseline Ventures and Andreessen Horowitz, and is poised to raise $40 million in a current funding round. But, some top venture-capital firms have decided not to invest because of the "app's high valuation and immaturity of its business."

For comparison, the social check-in app Foursquare raised $50 million in an investment last year, as did the newsreader Flipboard.

Another obstacle for Instagram is that the app is only compatible with iPhone, iPad, and iPod Touch. However, the company is currently working on a version that could run on Google's Android operating system.