In the 1970s, a CIA officer named Richards Heuer created a methodology to help intelligence analysts think clearly about complex problems. He called it Analysis of Competing Hypotheses. Since then, the methodology has spawned several software companions. In 2005, Heuer assembed a small team of intelligence and Web professionals to build a new one that would accommodate multi-member research teams and remote collaboration. We think ACH is a great way to think about problems and want it to be available to as many people as possible, so in the summer of 2010, we released the code under an open source license, allowing anyone download, modify, and use it for free.