About DiagBench

DiagBench is a free collection of browser-based tools for testing and diagnosing display problems — dead pixels, stuck pixels, backlight bleed, ghosting, refresh rate, resolution and color. Everything runs in your browser. There is nothing to install, no account to create, and nothing you test is ever uploaded.

What we believe

Honesty over hype. A web page cannot read the state of a physical pixel, so we never claim to “automatically detect” defects. Our tools show you the colors and patterns that make problems visible, then help you mark and interpret what you see. Any site that reports a precise number of dead pixels it “found” is guessing.

Your data stays with you. The few things we remember during a session — the defects you mark and the diagnoses you reach — live only in your browser tab for the length of your visit. We don’t send screen data, defect coordinates, or anything else to a server.

Useful, not bloated. Each tool is built to do one job well and load fast. We’d rather have a handful of genuinely good tests than dozens of thin ones.

How the tools work

Modern browsers can paint the entire screen a solid color, read basic display metrics like resolution and pixel ratio, and time animation frames precisely. That’s enough to cover the checks most people need. Where a browser hits a hard limit — measuring true color accuracy, for instance — we say so plainly and point you to the right tool for the job, such as a hardware colorimeter.

Who it’s for

Anyone checking a screen: buyers inspecting a new monitor, sellers documenting a used one, people troubleshooting a fault, and enthusiasts tuning a display. The tools work the same on desktops, laptops, tablets and phones.

Independence

DiagBench is independent and not affiliated with any monitor or device manufacturer. Some pages may link to relevant products; where a link is a paid affiliate link, we disclose it. Those links never change the results of a test.

Questions or feedback? See our contact page.