NSIS (Nullsoft Scriptable Install System) is a professional open-source tool for the development of Windows installers. It is designed to be as small and flexible as possible and is therefore highly suitable for internet distribution. NSIS is script-based and allows you to create the logic to handle even the most complex installation tasks. Many plug-ins and scripts are already available: you can create web installers, communicate with Windows and other software components, install or update shared components and more.