About Flicker Button

What it is

Flicker Button is a set of six free tests: a dead pixel test with a stuck pixel exerciser, a backlight bleed and uniformity test, a keyboard tester, a mouse tester, a refresh rate test and a gamepad tester. They are made for the moments when you unbox a new monitor, buy a second-hand keyboard, or start wondering why your mouse double-clicks on its own.

How it works

Every test runs in your browser with standard web features: full-screen pages, keyboard, mouse and pointer events, the animation timer and the Gamepad API. What you press, click or plug in is handled on the page and never sent anywhere. Once a page has loaded, its test keeps working without a connection. The site counts page views with Cloudflare Web Analytics, which uses no cookies and never receives what you do in the tests.

What a web page cannot measure

A browser only sees what your system passes on. Some keys and shortcuts never reach a page, a mouse's polling rate can be capped by the browser, and frame rates can be limited by power settings. Response time, input lag, brightness and colour accuracy need measuring hardware, so these tests do not claim to measure them. Each page explains its own limits.

A note on flashing

The stuck pixel exerciser flashes bright colours quickly. It only starts after you read a photosensitivity warning and press a button, and it stops with Esc. No other page flashes.