Device Tester
Check that a computer's keyboard, mouse, touchscreen, webcam, microphone, speakers, screen and game controller all work, straight from the browser. Handy before a video call, after a repair, or when someone says "my keyboard's broken".
- Nothing leaves your device
- Seven hardware tests
- Nothing to install
Press every key. Keys light up while held and turn green once they've worked. Shown as a UK keyboard; other layouts work too.
Scroll the keyboard sideways to see all of it.
Rollover and ghosting
Hold these keys down together. A combination turns green when every key registers at the same time. If one won't, the keyboard can't handle that combination (ghosting).
Recent keys
| Key | Code | Where |
|---|
Other keys we saw:
Some keys never reach a web page: Fn, most Windows key shortcuts, and keys your computer uses itself (like brightness and volume on many laptops). Print Screen often only shows when you let go of it.
Move the pointer into the box, then click each button, double-click, and scroll up, down and sideways.
Move in fast circles to measure the polling rate.
Touchscreen and pen
Touch the box with as many fingers as you can, or draw across it to find dead spots. Use full screen to test the whole display.
Your browser will ask to use the camera. The picture stays on this device: nothing is recorded or uploaded.
Your browser will ask to use the microphone. Sound stays on this device: recordings are kept in this page until you close it.
Record and play back
- Noise suppression removes steady background noise like fans and traffic. Echo cancellation stops the other person hearing themselves through your speakers. Automatic volume evens out loud and quiet speech. Video call apps turn these on; untick them to hear what the microphone really picks up.
- Can't hear anything? Check the microphone isn't muted (many headsets and laptops have a mute switch or key), that the right one is picked, and in Windows that Settings > Privacy & security > Microphone lets apps and your browser use it.
Left and right
In phase should sound centred and full. Out of phase sounds thin and hard to place. If they sound the other way round, one speaker's wires are swapped (+ and −).
Frequency sweep and tones
- Listen for buzzing or rattling during the sweep: it points to a loose or damaged speaker. Small laptop speakers produce little below about 150 Hz, which is normal.
- Most adults can't hear above 15 to 17 kHz, so silence at the top of the sweep is usually your ears, not the speakers.
What your browser reports about this screen, plus full-screen tests. In a test, click or press Space or the arrow keys for the next pattern, and Esc to finish.
Full-screen tests
Dead pixels stay black on every colour; stuck pixels stay one colour. Do the black tests in a dark room with brightness turned up to see backlight bleed around the edges.
Every test runs inside your browser. Camera pictures, microphone sound, recordings and key presses never leave this device, and the camera and microphone switch off when you leave their tab.
Keyboard problems
- A key never lights up: try another USB port or fresh batteries, and clean under the key. On laptops, a few dead keys in a row usually means the keyboard needs replacing.
- A key lights up on its own or stays lit: it's stuck or there's liquid damage. Unplug the keyboard and check again.
- Letters appear twice: worn switches "chatter". We flag it when the same key registers twice within a few milliseconds.
- Wrong symbols, like @ and " swapped: the keyboard is fine but Windows is set to a US layout. Change it in Settings > Time & language > Language & region.
Mouse and touchpad problems
- Single clicks act as double-clicks: a worn button switch. We warn when two clicks arrive faster than a person can click.
- Scrolling jumps backwards: a worn or dirty scroll wheel. We count it when the wheel suddenly reverses mid-scroll.
- Polling rate is how often the mouse reports its position. Office mice report 125 times a second, gaming mice 500 to 1,000 or more. The browser may cap what it can see, so treat it as a guide.
- Back and forward buttons may take your browser to the previous page if pressed outside the test box.
Camera and microphone problems
- Permission denied: click the camera or padlock icon in the address bar and allow access, then try again. In Windows, check Settings > Privacy & security > Camera (or Microphone).
- "In use" or a black picture: close Teams, Zoom and other apps that may be holding the camera. Check for a privacy shutter or a camera off key (often F8 or F10 on laptops).
- Low frame rate: usually poor lighting. Webcams slow down to let in more light.
- The tests here use the same browser features as web video calls, so if they work here, a call in the same browser should too.
Screen checks
- Dead or stuck pixels: check each solid colour closely. Most makers only replace a screen with several faulty pixels, so check the warranty's pixel policy.
- Banding: stripes in a smooth gradient. Some is normal on cheaper 6-bit panels and with night light or colour filters on.
- Refresh rate: if a 120 Hz or 144 Hz screen shows 60 Hz, set it in Settings > System > Display > Advanced display, and check the cable supports it. Battery saver can also lower it.
- HDR and colour gamut show what the browser can use right now, which depends on Windows' HDR setting as well as the screen.
Questions
Is anything recorded or uploaded?
No. All the tests run in your browser. Snapshots and recordings stay in this page until you save them or close it. We only count which tests are used, with no content.
Why can't the page see my Fn key or some media keys?
Those keys are handled by the keyboard or by Windows before the browser sees them. If the volume changes when you press a volume key, it's working even if it doesn't light up here.
Does it work on phones and tablets?
Yes: the touchscreen, camera, microphone, speaker and screen tests work on phones and tablets. iPhones can't show the touch test full screen, and Low Power Mode can lower the refresh rate we measure.
My controller isn't showing up
Press a button on it: browsers hide controllers until you do. If it still doesn't appear, try a cable instead of Bluetooth, or check it shows in Windows under Settings > Bluetooth & devices.