(UPDATED) SoundTracking, an addictive social mobile iPhone app that creates “musical postcards”, has received $4.75 million in financing. SoundTracking is currently the most shared music service on Twitter.

The company will use a portion of the funding to expand to the Android platform.

The financing round was led by Accel Partners, also an investor Spotify, along with True Ventures and SoftBank Capital.

“There are a lot of music services out there that allow people to consume, and then offer sharing as an additional feature,” Steve Jang, the company’s co-founder, told the New York Times. “We are making sharing the core experience and discovery is a bi-product.”

SoundTracking was developed in San Francisco based mobile app incubator and previously received $1.1M in seed funding from True Ventures, Google Ventures and AOL Ventures.