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:

• Internet Information Services
• WebMatrix
• Visual Web Developer Express Edition
• Microsoft SQL Server Express Edition
• .NET Framework
• Silverlight Tools for Visual Studio
• PHP
• WordPress
• Umbraco
• Drupal
• Joomla!
• Orchard

The ability to install third-party software was added in version 2.0, released September 24, 2009.^[3] As of July 2015, Web PI can install 82 titles.^[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.^[5]

On July 7, 2010, Microsoft announced Web PI 3 which includes WebMatrix, a new set of integrated tools for web development. Web PI 3 installs additional tools for web development including IIS Developer Express, SQL Server Compact and DotNetNuke.

Web PI features an offline mode where products can be downloaded to a local cache on a machine where internet access is available and then use these cached files on a different machine later.^[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.^[7]

• Solution stack: set of software subsystems or components needed to create a complete platform
• Windows Package Manager: an open-source package manager for Windows 10 and Windows 11

• Official website
• Introduction to WebPI and WebPI Command-Line Utility