You are maintaining an existing production application, working with legacy hardware, or using a 3rd party SDK that requires 32-bit.
Since the is no longer officially distributed (Qt now requires account login for online installer), see: qt-opensource-windows-x86-5.15.2.exe
qt-opensource-windows-x86-5.15.2.exe is a time capsule. It is battle-tested, stable, and will likely compile your code perfectly for the next decade. Last updated: April 2025
Last updated: April 2025. This article reflects the state of Qt distribution as of this date. Filename and availability subject to change by The Qt Company. Qt 5 to Qt 6 Migration Guide (cross-version,
Qt 5 to Qt 6 Migration Guide (cross-version, but references 5.15 changes)
: After installation, set up your development environment. This typically involves setting the PATH environment variable to include the Qt tools (like qmake , lupdate , lrelease , etc.) and ensuring that your IDE (Integrated Development Environment) or text editor is configured to use the Qt libraries.