Device Testers

Before you blame a game, a video call, or a stream for lagging, cutting out, or feeling “off,” it’s worth ruling out the hardware itself. Device Testers is a single page that checks your keyboard, mouse, screen, and phone’s vibration motor — no downloads, no account, and nothing you type or click is sent anywhere. Everything runs locally in your browser tab and disappears the moment you close it.

Most keyboard and mouse test sites online only tell you whether a key or button registers at all. This one goes further: it tracks how many keys your keyboard can register at once (its rollover limit), flags mouse clicks that fire suspiciously close together — a classic sign of a worn-out switch causing accidental double-clicks — and estimates your mouse’s real-world polling rate by timing how often movement events actually arrive. None of that requires installing anything.

What you can test

Keyboard — A full on-screen layout lights up as you type, key by key, so you can see at a glance which keys are working, which are unresponsive, and which are stuck. A rollover counter shows the maximum number of keys your keyboard successfully registers when held down together, which matters if you play games or type quickly and notice certain key combinations getting dropped. A built-in typing test also gives you words-per-minute and accuracy if you just want to know how fast you type.

Mouse — Click zones track your left, right, and middle button counts separately, and the tool automatically watches for clicks that land less than 50 milliseconds apart — a strong signal of the double-click switch fault that eventually affects most mice. A scroll-wheel counter, a 5-second clicks-per-second test, and a live polling-rate estimate round out the mouse checks.

Screen — See your screen’s real resolution, viewport size, pixel density, and color gamut, then run a full-screen dead-pixel test that cycles through solid colors so stuck or dead pixels stand out. A separate refresh-rate estimate uses your browser’s own rendering loop to approximate your monitor’s real Hz.

Vibration — On supported phones, test your device’s vibration motor with preset patterns (short buzz, long buzz, double pulse, SOS) or build your own custom pattern.

How to use it

1. Open the tool and pick a tab — Keyboard, Mouse, Screen, or Vibration.
2. For the keyboard test, click the on-screen keyboard area to focus it, then start typing normally or run through every key you want to check.
3. For the mouse test, click and scroll inside the test zones, or start the 5-second CPS test and click as fast as you can.
4. For the screen test, launch the full-screen pixel test and step through each color with a click, tap, or arrow key, looking closely for any spot that doesn’t change.
5. Switch tabs anytime — each test keeps running independently, and nothing is saved or logged after you leave the page.

Frequently asked questions

Does this work without installing anything? Yes. It’s a browser page — no extension, no app, no signup. It works on desktop and mobile browsers, though the vibration test only applies to phones that support it.

Can this actually diagnose a broken mouse switch? It can give you strong evidence. If the click test repeatedly flags clicks under 50 milliseconds apart when you’re only clicking once, that’s a well-known symptom of mechanical switch wear causing false double-clicks — common on mice that are a couple of years old.

Why does my mouse’s polling rate show lower than the number on the box? Browsers can only report movement as fast as the page actually renders it, so very high polling-rate mice (500Hz–1000Hz+) often get capped by your display’s refresh rate in this kind of test. Treat the number as a rough estimate, not a spec-sheet match.

Will the keyboard test detect ghosting? Indirectly — the on-screen keyboard shows exactly which keys register when several are held down together, so if a key silently fails to light up during a multi-key combo, that’s ghosting or blocking happening in real time.

Is my data uploaded anywhere? No. Every test runs entirely in your browser using standard web APIs (keyboard/mouse events, the Vibration API, canvas rendering). Nothing is sent to a server, logged, or stored after you close the tab.

Does the vibration test work on iPhone? No — iOS Safari doesn’t expose the Vibration API to websites. This test only works on Android and other browsers that support it; the page will tell you plainly if your device doesn’t.

Related tools

If you’re troubleshooting a device more broadly, the User-agent parser can show you exactly what your browser is reporting about your operating system, device type, and hardware — useful if a site or app is behaving differently than expected. The QR code scanner is handy if you’re testing a phone’s camera at the same time. And if you just need a quick stopwatch running alongside a hardware test, the Countdown timer / stopwatch tool covers that.