Third Party Tools
For every serious software development you need tools. Here is a list of tools we use to develop FreeCAD:
Platform independend tools
Great vector drawing programm. Adheres to the SVG standard and is used to draw Icons and Pictures. Get it at www.inkscape.org.
A very good and stable tool to generate source documentation from the .h and .cpp files.
Not much to say about the GNU Image Manipulation Program. Besides it can handle .xpm files which is a very convenient way to handle Icons in QT Programms. XPM is basically C-Code which can be compiled into a programm. Gimp product the free .png format used in the wiki.
Get the GIMP here: www.gimp.org
This is a proprietary git GUI that is very helpful to learn how git works if you're interested in wanting to contribute to FreeCAD. Relevant pages to research:
Free and open source software for video recording and live streaming. More details on official website : obsproject.com
A full featured UML programm. It has a lot of features of the big ones, including reverse engineering C++ source code....
Download here: staruml.io
Tools on Windows
Visual Studio Community
Visual Studio Community is free for open source projects and small structures. Installation is modular you can add support for a large variety of language including C++ and python.
It can be downloaded at 
Is a Open Source tool to record Screencasts (Webcasts). Its a very good tool to create tutorials by recording them. Its far not so boring as writing documentation.
See camstudio.org for details.
Tools on Linux