AddThis Indeed: Clearspring Raises $20 Million As It Rides Social Sharing Boom

The name Clearspring Technologies may not be terribly familiar to you, but chances are you've often clicked on or at least come across its AddThis buttons, which are plastered on publisher sites Web-wide. The U.S.-based social sharing platform company this morning announced that it has raised a whopping $20 million in a Series D round of funding led by Institutional Venture Partners , with existing backers such as NEA and Novak Biddle Venture Partners participating.