.NET Version Detector is a little utility which - as the name already suggest - detect the current installed .NET Framework version on Windows systems. The latest version now detects 4.7.1 which is the pre-installed Windows 10 Creators Update .Net Framework version.
The program works from Windows 7 up to Windows 10 and is portable which means you download the package, extract it and run the little application, it doesn’t needs to be installed, the little download buttons on the left side linking to the official .NET Framework versions on the Microsoft page, which allows you - if you want - to install the missing versions. Windows 10 comes already pre-installed with all versions except .NET Framework 3.5, which can be optional activated/installed via the Programs and Features Wizard.
The program is a good and quick solution if you unsure which versions are installed and if you not want to search in the Registry.