A free, privacy-first browser utility built to evaluate, inspect, and troubleshoot computer monitors, laptops, mobile devices, and TVs without software installation.
Buying a new or used monitor often involves uncertainty: dead pixels, backlight bleed, washed-out contrast, and ghosting are difficult to identify during brief in-store checks or unboxings. Monitor Tester was created to provide a complete, accessible suite of diagnostic patterns that anyone can run immediately in any modern web browser.
Every test runs locally on your device using standard HTML5 Canvas, WebGL, CSS hardware acceleration, and the Screen and Window APIs. No downloads, native installers, or administrative permissions are needed. Your display data stays entirely on your computer.
Detect dead pixels, stuck subpixels, bright subpixels, and panel image retention (burn-in) across pure color fields.
Evaluate continuous gradients, color banding steps, color gamut boundaries, and multi-step grayscale ramps.
Tune near-black and near-white clipping, check dark-room backlight bleeding, and assess full-screen brightness uniformity.
Check ghosting trails, evaluate pixel overdrive settings, measure V-Sync refresh rate (Hz), and inspect for screen tearing.
Inspect detected screen metrics (DPR, color depth), calculate PPI and optimal viewing distances, compare displays, and test multi-touch.
Monitor Tester is an open-source project. You can inspect the source code, report rendering bugs, suggest new test patterns, or contribute directly on GitHub.
View project on GitHub