Display Tester is a utility and tool application developed by Braintrapp for Android devices. It enables users to test almost every aspect of their device's LCD/OLED screen. The app is designed to allow full-screen testing even on devices with soft keys, and it hides the soft keys in immersive mode in KitKat and later versions.

The app's free features include a dead pixel test, color tests like contrast, gradient, and saturation tests, gamma calibration tests, wide gamut color tests, viewing angle tests, multi-touch tests, display performance tests, repair burn-in, display measures info, real-world pictures for reference and comparison, pixel format and dithering tests, and more. The app also offers pro features like full Google Cast support and repair burn-in noise.

Users can use gestures like slide left-right to change test image, slide up-down to change brightness, long touch to switch between full screen and normal screen, and double tap to hide or show the test specific settings dialogue. The app also includes a touch screen dead spot tester, system fonts tester, and DIP/PX calculator.

Overall, Display Tester is a comprehensive tool that offers a wide range of features for testing and calibrating your device's screen. Please note that the pro version must be purchased to access some advanced features and to support further development.