There are many websites and apps, which help us to determine the Internet speeds. Among those very popular is Ookla Speedtest. It has a website called speedtest.net which is widely used to check the download/upload speeds as well as Ping. Now Ookla has released a standalone app for Windows 10 where you can check the speeds in a click. You can download this app from windows store.
It has a very simple user interface with a single “Go” button on the main screen. History tab allows you can check all the speed tests you have conducted. Even you can share the test results to apps like Twitter, Messengers, or Outlook. You cannot maximize the app as it runs on the mobile layout.
Update : Latest update of Speedtest includes support for resizing app.