A set of free browser tools for testing and using screens.
Everything here runs in your browser. Open a page, use the tool, close the tab.
Nothing to sign up for, nothing to remember.
Every tool is a web page. No app, no extension.
No gate, no newsletter, no unlock.
What you make stays on your own device.
Where it came from
The site began with a broken monitor and a search that went nowhere. Checking for dead pixels should take thirty seconds: fill the screen with one color at a time and look at it. Instead the results were a mix of pages that wanted an app installed, pages buried under advertising, and pages that showed a color but nothing else — no way to step through a sequence, no guidance on what a fault actually looks like, no next step once you found one.
That gap turned out to be the whole idea.
The individual tools are simple by nature. What was missing was somewhere that had all of them, that loaded instantly, and that told you what to do next.
The diagnostics are the ones the site is really built around: Dead Pixel Test, Backlight Bleed Test, Screen Uniformity Test, OLED Burn-In Test and a guided Monitor Test that runs the checks in order for anyone who is not sure where to start. The rest exists because a screen is also something you use: colors to light a video call, sounds and timers to focus by, screensavers, wallpapers and a few harmless pranks.
Three things guide how it is built
It runs on your device
Every page is a plain file, and every tool works in your browser. There is no server doing work in the background and no account holding anything about you. Nothing you do with a tool is uploaded.
It is honest about its limits
A browser cannot measure light, color or response time. Where a tool can only show you something rather than measure it, the page says so, instead of dressing a guess up as a measurement.
It is careful by default
Nothing here is designed to flash. Moving screens start only when you press a button, sound starts only when you ask for it, and everything stops when you leave the page.
Who runs it
ScreenTail is run by Vivek Kumar, personally, from New Delhi, India. There is no company behind it.
Vivek decides what each tool does and what goes on the site, and nothing is published until it has passed the automated checks described on How We Test. He has also checked the site himself on a phone, a laptop and a 4K monitor.
The site is free to use, with no advertising and no affiliate links.
If something is broken
Reports of tools behaving oddly on unusual hardware are especially welcome: that is exactly the thing one person cannot test alone. Write to contact@screentail.com or see the contact page, and include the tool, your device and your browser.
Not sure whether it is your screen or the tool? The Monitor Test walks through the checks in order and is usually the fastest way to tell.