Download latest stable release automatically
Win32 Installation guide
POSIX Installation guide
MacOS Installation guide
Sources are available on github.
Stable releases are published at Sourceforge.net. You can download them at https://sourceforge.net/projects/upp/files/.
You do not have to pay anything for Ultimate++, even if you are going to use it for development of commercial applications. However, if you like this platform, please consider donating; even small contributions will help fund its continued development.