pfSense is brought to you by a dedicated group of developers who are security and network professionals by trade. The following people are active developers of the pfSense project. Username is listed in parenthesis (generally also the person's forum username, IRC nickname, etc.). 

You can follow the developers on Twitter here. 

Founders
In alphabetical order

Chris Buechler (cmb)
Scott Ullrich (sullrich)

Active Developers
Listed in order of seniority along with date of first contribution.

Bill Marquette (billm) - February 2005
Holger Bauer (hoba) - May 2005
Erik Kristensen (ekristen) - August 2005
Seth Mos (smos) - November 2005
Scott Dale (sdale) - December 2006
Martin Fuchs (mfuchs) - June 2007
Ermal Luçi (ermal) - January 2008
Matthew Grooms (mgrooms) - July 2008
Mark Crane (mcrane) - October 2008
Jim Pingle (jim-p) - February 2009
Rob Zelaya (robiscool) - March 2009
Renato Botelho (rbgarga) - May 2009

FreeBSD Developer Assistance
We would like to thank the following FreeBSD developers for their assistance.

Max Laier (mlaier)
Christian S.J. Peron (csjp)
Andrew Thompson (thompsa)
Bjoern A. Zeeb (bz)

among many others who help us directly, and everyone who contributes to FreeBSD. 

Inactive Developers
The following individuals are no longer active contributors, having moved on because of other commitments, or employers forbidding contributions. We thank them for their past contributions.

Daniel Berlin (dberlin)
Daniel Haischt (dsh)
Espen Johansen (lsf)
Scott Kamp (dingo)
Bachman Kharazmi (bkw)
Fernando Tarlá Cardoso Lemos (fernando)
Kyle Mott (kyle)
Colin Smith (colin)