Screen Checker — Dead pixels, color, resolution

1. What does this tool do

This free online screen checker helps you diagnose display issues and view display info in one place. Use it for dead pixel test, monitor test, or screen test with solid-color tests for dead and stuck pixels, gradients for banding, and patterns for sharpness. Check resolution, color depth, and orientation from your browser. No install, no upload; everything runs in your browser and no data is sent to any server. Ideal for dead pixel check, color accuracy, backlight bleed, sharpness, or display info for support.

2. How to use it

Quick start: View display info (resolution, color depth, etc.), select a test (Black, White, Red, Green, Blue, Grayscale, gradients, Checkerboard, Grid), enter fullscreen for best dead-pixel testing, then inspect for dark spots (dead) or bright dots (stuck).

1. Display info — View resolution, available size, color depth, device pixel ratio, and orientation. Click the copy icon to copy any value.
2. Select a test — Click a test button (Black, White, Red, Green, Blue, Grayscale, RGB Horizontal, RGB Vertical, Checkerboard, or Grid) to display that pattern in the test area.
3. Fullscreen — Click Enter fullscreen to expand the test area to your entire screen. Recommended for dead pixel testing. Press Escape or click Exit fullscreen to exit.
4. Inspect — Look for dark spots on bright screens (dead pixels) or bright dots on dark screens (stuck pixels). Use gradients to check for color banding; use patterns to verify sharpness.

3. How it works

• Solid colors — Full-area backgrounds in black, white, red, green, and blue. Rendered with CSS backgroundColor.
• Gradients — Linear gradients (grayscale, RGB horizontal/vertical) to detect color banding and uniformity. Rendered with CSS linear-gradient.
• Patterns — Checkerboard and grid for pixel alignment and sharpness. Rendered with CSS repeating-conic-gradient and linear-gradient.
• Display info — Read from window.screen (width, height, availWidth, availHeight, colorDepth, pixelDepth, orientation) and window.devicePixelRatio. All processing runs entirely in your browser. No data is sent to any server.

4. Use cases & examples

• Dead pixel check — Use solid black and white screens. Dark spots on white indicate dead pixels; bright dots on black indicate stuck pixels.
• Color accuracy — Use RGB gradients to check for color banding (visible steps instead of smooth transitions).
• Backlight bleed — Use the black screen in a dark room. Light leaking from edges or corners indicates backlight bleed.
• Sharpness — Use the grid or checkerboard to verify lines are crisp and pixels align correctly.
• Display info — Copy resolution and color depth for support tickets, compatibility checks, or development.

Example

• Select Black → full black screen; look for bright stuck pixels.
• Select White → full white screen; look for dark dead pixels.
• Enter fullscreen → test area fills entire display for accurate diagnosis.

5. Limitations & known constraints

• Browser viewport — In normal (non-fullscreen) mode, the test area is limited to the page content. Use fullscreen for full-display coverage.
• Screen API limits — Display info reflects what the browser exposes. Multi-monitor setups may report primary or current display only.
• No persistence — No data is stored. All info is read on load and displayed in memory.