Screen Tester Pro od BeYor

Screen Tester Pro gives you instant access to 10 professional display test patterns directly in your browser:

RGB & CYMW - check color purity and accuracy
Gradient - detect banding and bit-depth issues
Checkerboard (3 sizes) - pixel sharpness and contrast
Focus text - font rendering at all sizes
Dead pixels - auto-cycling solid colors to spot stuck pixels
256 colors - full spectrum and grayscale ramps
Backlight bleed - pure black for dark-room edge testing
Geometry - straight lines, diagonals, and circle for distortion
Gamma - dither matching to verify gamma accuracy
Subpixel - single-pixel alternating colors for fringing

Features:
✓ Fullscreen mode (F key)
✓ Hide UI for unobstructed testing (H key)
✓ Keyboard shortcuts for all patterns (1–0, arrow keys, Space)
✓ Brightness overlay slider (+/- keys)
✓ Mouse coordinate display
✓ Built-in help screen (? key)
✓ Works 100% offline — no data sent anywhere