jstest-gtk is a simple joystick tester based on Gtk+. It provides you with a list of attached joysticks, a way to display which buttons and axis are pressed, a way to remap axis and buttons and a way to calibrate your joystick.
Even when your joystick is working mostly fine, you might want to give it a try, as the calibration lets you get rid of overlarge default deadzones that many joysticks use and that are a a noticable problem in some games.
jstest-gtk is covered under the GPLv3.
You can get jstest-gtk from github.
This is a list of prebuild versions of jstest-gtk. Note that these are not build by myself, so don't ask me questions about them:
© 2009 Ingo Ruhnke <firstname.lastname@example.org>