Finding the original standalone .exe today can be challenging due to changes in how The Qt Company distributes older versions: Qt 5.15.2 Released
If you strictly require an offline environment, you must build the framework yourself. Source Code : You can download the source package (e.g., qt-everywhere-src-5.15.2.zip ) from the Qt Archive Requirement : This requires a compiler like and can be a complex process. 3. Alternative Tools aqtinstall qt-opensource-windows-x86-5.15.2.exe