Ways to check if a controller has been detected by Windows - R7's DS4Windows Website (Unofficial)
Hello r/gamedev, I made this free little tool to test out controller inputs, since there's hardly a way to test them out without running a game or some other unrelated software :
HTML5 Gamepad Tester - Test your gamepad online! — Steemit
GamePad Viewer - The Official Controller Display & Tester