DuckDuckGo was solo-founded by Gabriel Weinberg in February 2008 in Valley Forge, PA (USA).
It was self-funded until October 2011, when it was backed by Union Square Ventures and a handful of angel investors. Since the funding, the team has expanded to around 40 employees and a bunch of open-source contributors.
For a more detailed DuckDuckGo history, check out our Wikipedia entry.
For more information about DuckDuckGo's contributors, visit our team list on Twitter.