Web Platform Installer (Web PI) was a freeware, closed-source package management system that installs non-commercial development tools and their dependencies that are part of Microsoft Web Platform, including: The ability to install third-party software was added in version 2.0, released September 24, 2009.

[4] Web PI 2.0's options are populated dynamically at runtime from Microsoft's servers, allowing installation options to be updated without the need to download newer versions of the Web PI itself.

Web PI 3 installs additional tools for web development including IIS Developer Express, SQL Server Compact and DotNetNuke.

[6] However, Web PI is still not usable in environments where Internet connectivity and local administrator privileges are mutually exclusive (i.e. a given process can either authenticate through a transparent proxy, or can have High or System integrity level, but not both).

The Microsoft Web Platform Installer (WebPI) has been retired since July 1, 2022.