Foursquare plans to start charging companies making the heaviest use of its vast local-business database. The massive resource has gradually been enhanced through the years as Foursquare has grown and compiled over 6 billion user check-ins. Thanks to all that activity, the company's location database is seen by many as superior to similar services from Facebook and others. (Many users were displeased when Instagram moved away from Foursquare in favor of Facebook's solution.) Foursquare obviously risks angering developers and pushing them to research other options by charging for access, but COO Jeffrey Glueck told The Wall Street Journal that the fees will impact less than 1 percent of companies currently pulling from its database.

Twitter, Yahoo, and Pinterest may be among those required to pay up, but most third-party developers don't yet need to worry about forking cash over to Foursquare. "We are committed to supporting our developer ecosystem," Glueck told the Journal. Where applicable, deals will be worked out on an individual basis with each company; there's no flat rate that will affect everyone. The decision could produce a new source of revenue for Foursquare, which has found it difficult to base its business around advertising alone — the company charges nothing for its mobile applications Foursquare and Swarm. Earlier this year, Microsoft announced a $15 million investment in Foursquare. In exchange for the funding, it struck a licensing deal that will see Foursquare's wealth of location data integrated across Windows and Bing.