Just came across this nice little site that Scott Hanselman put together to evaluate your machine’s .NET Framework version and provide a simple JSON payload to get direct access to the .NET Framework installers.
How it Works?
“This site looked at your browser's "UserAgent" and figured out what version (if any) of the .NET Framework you have (or don't have) installed, then calculated the total size if you chose to download the .NET Framework.
There's no database, no cookies, and nothing about your computer has been stored or kept. We just look at the information your browser already reports about your computer and make a suggestion as to the best .NET Framework download for you.”
Here is Hanselman’s blog post about the site and how to use it. Clever, helpful tool.