QGIS is a user friendly Open Source Geographic Information System (GIS) licensed under the GNU General Public License. QGIS is an official project of the Open Source Geospatial Foundation (OSGeo). It runs on Linux, Unix, Mac OSX, Windows and Android and supports numerous vector, raster, and database formats and functionalities.
QGIS is a volunteer driven project. Contributions to the project in the form of code contributions, bug fixes, bug reports, contributed documentation, advocacy and supporting other users on the mailing lists and gis.stackexchange.com.
Office of Public Works, Ireland, Ireland (12.2014-12.2016)
GAIA mbh, Germany (11.2015-11.2016)
Sourcepole AG, Switzerland (10.2014-10.2016)
AGH University of Science and Technology, Poland (06.2015-06.2016)
State of Vorarlberg, Austria (03.2013-05.2016)
Teaching Jobs with Footprints, Canada (04.2016-04-2017)
National Parks UK, United Kingdom (03.2016-03-2017)
KBB Underground Technologies, Germany (03.2014-03.2017)
BGEO OPEN GIS, SL, Spain (03.2016-03-2017)
Ager Technology, Spain (03.2014-03.2017)
Asociación Geoinnova, Spain (03.2016-03-2017)
Gis3W, Italy (01.2014-01.2017)
GIS-Support, Poland (02.2015-03-2017)
www.molitec.it, Italy (01.2014-03.2017)
Chartwell Consultants Ltd., Canada (03.2015-03.2017)
Trage Wegen vzw, Belgium (03.2015-03.2017)
GKG Kassel,(Dr.-Ing. Claas Leiner), Germany (03.2014-03.2017)
CawdorForestry Resource Management, Scotland (02.2016-02.2017)
ChameleonJohn, USA (02.2016-02.2017)
2D3D.GIS, France (12.2015-12.2016)
Dr. Kerth + Lampe Geo-Infometric GmbH, Germany (12.2015-12.2016)
MappingGIS, Spain (11.2015-11.2016)
HostingFacts.com, Estonia (12.2015-12.2016)
Urbsol, Australia (11.2014-11.2016)
Lutra Consulting, UK (10.2015-10.2016
WhereGroup GmbH & Co. KG, Germany (08.2015-08.2016)
Nicholas Pearson Associates, UK (07.2015-07.2016)
QGIS Polska, Poland (07.2015-07.2016)
www.terrelogiche.com, Italy (06.2015-06.2016)
www.geosynergy.com.au, Australia (05.2012-05.2013+06.2015-06-2016)
Gaia3D, Inc., South Korea (05.2015-05.2016)
Royal Borough of Windsor and Maidenhead, UK (04.2015-04.2016)
Map of users between Oct 23, 2011 and Dec 17, 2011 who downloaded the PyQGIS plugin. Source
QGIS US User Group
QGIS Australian & New Zealand User Group
QGIS UK User Group
QGIS Italy User Group
NIWA QGIS User Group
QGIS Portugal User Group
Puget Sound QGIS
QGIS Switzerland User Group
This is a very small sampling of universities across the Globe who use QGIS
UNITED STATES
Columbia University
Cornell University
Duke University
George Mason University
Harvard University
Michigan State University
University of Colorado
University of Michigan
CANADA
Brock University
University of Toronto
AFRICA
University of Cape Town
ASIA
Nusa Cendana University, Indonesia
Padang State University, Indonesia
EUROPE
Maynooth University, Ireland
Stockholm University, Sweden
University of Copenhagen, Denmark
UNITED KINGDOM
Newcastle University
University of Leicester
University of Southampton
University of Sussex
OCEANIA
University of Sydney, Australia