NSIS (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.
Being a user’s first experience with your product, a stable and
reliable installer is an important component of succesful software.
With NSIS you can create such installers that are capable of doing
everything that is needed to setup your software.
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.