NSIS is described as '(Nullsoft Scriptable Install System) is a professional open source system to create Windows installers. It is designed to be as small and flexible as possible and is therefore very suitable for internet distribution' and is a popular app in the OS & Utilities category. There are more than 50 alternatives to NSIS for a variety of platforms, including Windows, Linux, Mac, BSD and Wine. The best alternative is Inno Setup, which is both free and Open Source. Other great apps like NSIS are WiX (Free, Open Source), Advanced Installer (Freemium), install4j (Paid) and Venis GUI for NSIS (Free).
Creating professional setup files used to require script-powered installers, which meant learning new scripting languages and mastering complex installer maker solutions. Now there is an easier way to create great setup files.