Freeware is, as the name suggests, available free of charge. Often produced by enthusiasts, free ware can be exceptional quality. Types of freeware includes AFCAD files, General Aviation, Commercial and Military aircraft. Also, extensions such as panels and gauges, scenery, and other utilities. You can also find free flight simulator software available from some of the main publishing houses. These tend to be either old, or trial software. They represent excellent value for money. You can find many unusual aircraft types amongst these files. When you cannot find a particular 'payware' aircraft then you can often find them in this category.
Simviation is a massive resource for Freeware addons for Microsoft Flight simulator series, Lockheed Martin Prepar3D (P3D), FSX, FS2004, Combat Flight Simulator and other PC Flight Simulation products like Xplane & Flightgear!