ActiSetup is a rapid development environment for building setup packages. It allows developers to make installers for their applications. It utilizes the Dacris Installer engine, a scripting engine that allows developers to create custom installations for their software products, and is built with pure Win32 API for maximum efficiency. One of the unique features of Dacris Installer is that it can download packages from the Internet very efficiently, using multiple threads and resume support, like a download manager.