HootSuite, a Web-based social dashboard, has 4 million users, the company said.
HootSuite netted its first million users over a two-year period and its final million in just four months. The fastest growth occurred in the U.S. and Europe.
Update: The company hit the benchmark in August, a spokesperson clarified over email.
HootSuite supports Twitter, Facebook, Google+ pages but not profiles, LinkedIn, Foursquare, MySpace, WordPress and Mixi. The service allows users to schedule posts and to edit tweets before re-tweeting them.