System Security and Antivirus
Comodo Antivirus
Comodo Personal Firewall
Avast
Notepad++
Notepad++ is a free (as in "free speech" and also as in "free beer") source code editor and Notepad replacement that supports several languages. Running in the MS Windows environment, its use is governed by GPL License.
PDF Editor
PDF Xchange Editor
The smallest, fastest, most feature-rich FREE PDF editor/viewer available!
Create, View, Edit, Annotate, OCR and Digitally Sign PDF files plus much more..
Media Player
KLite Mega Codec Pack
The K-Lite Codec Pack is a collection of DirectShow filters, VFW/ACM codecs, and tools. Codecs and DirectShow filters are needed for encoding and decoding audio and video formats. The K-Lite Codec Pack is designed as a user-friendly solution for playing all your audio and movie files. With the K-Lite Codec Pack you should be able to play all the popular audio and video formats and even several less common formats.
VLC Media Player
VLC is a free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVDs, Audio CDs, VCDs, and various streaming protocols.
QGIS
FreeCAD
FreeCAD is a general purpose parametric 3D CAD modeler. The development is completely Open Source (LGPL License). FreeCAD is aimed directly at mechanical engineering and product design but also fits in a wider range of uses around engineering, such as architecture or other engineering specialties
Sketchup
Blender
Blender is the free and open source 3D creation suite. It supports the entirety of the 3D pipeline—modeling, rigging, animation, simulation, rendering, compositing and motion tracking, even video editing and game creation.
Graphic Design and Multimedia Editor
GIMP
GIMP is a cross-platform image editor available for GNU/Linux, OS X, Windows and more operating systems. Whether you are a graphic designer, photographer, illustrator, or scientist, GIMP provides you with sophisticated tools to get your job done. You can further enhance your productivity with GIMP thanks to many customization options and 3rd party plugins.
Handbrake
HandBrake is a tool for converting video from nearly any format to a selection of modern, widely supported codecs.
Avidemux
Avidemux is a free video editor designed for simple cutting, filtering and encoding tasks.
VirtualDub
VirtualDub is a video capture/processing utility for 32-bit and 64-bit Windows platforms (98/ME/NT4/2000/XP/Vista/7), licensed under the GNU General Public License (GPL). It lacks the editing power of a general-purpose editor such as Adobe Premiere, but is streamlined for fast linear operations over video.
Inkscape
Inkscape is a professional open-source vector graphics editor similar to Adobe Illustrator and Corel Draw.
Audacity
Audacity® is free, open source, cross-platform audio software for multi-track recording and editing
Office Suites
Libre Office
LibreOffice is a free and open source office suite, a project of The Document Foundation. The LibreOffice suite comprises programs for word processing, the creation and editing of spreadsheets, slideshows, diagrams and drawings, working with databases, and composing mathematical formulae.
OpenOffice
Apache OpenOffice - formerly known as OpenOffice.org - is an open-source office productivity software suite containing word processor, spreadsheet, presentation, graphics, formula editor, and database management applications.
ZIPping and Archiving
7-Zip
7-Zip is a file archiver with a high compression ratio