NationBuilder is a community organizing software platform that helps people organize and build community-based relationships.

NationBuilder is software for leaders. The company was founded in November 2009 by Jim Gilliam, in partnership with Co-Founders Jesse Haff and Lea Endres, and launched in April 2011. By the summer of 2012, the company had secured more than $14 million in Series A and Series B funding led by Andreessen Horowitz and Omidyar Network, and added Ben Horowitz, Stacy Donohue, and Sean Parker to its board. Jim Gilliam became Executive chairman in fall of 2017 and welcomed Lea Endres to the role of CEO. NationBuilder is based in downtown Los Angeles with offices in New York, Washington DC, Vancouver, and London.

Founders:  Jesse Haff, Jim Gilliam, Lea Endres