TestSweep

Test your computer, one part at a time

Pick the part that is giving you trouble, or run the whole check. Every test runs inside this page — nothing is uploaded, nothing is installed.

Start the full checkRuns entirely in your browser

Check the screenCheck the webcamLeft, right and balanceCheck the microphoneTest every keyButtons and stick driftDouble-click and driftTouchscreen and sensors

Start with the phone in your hand

Touchscreen and sensorsTouchscreenDead zones and ghost touchesCheck the webcamCameraCheck the microphoneMic
Nothing checked yet

Start from what is wrong

Each one goes straight to the test or the checklist that settles it.

Monitor

  1. Screen resolution and display detailsSee your real screen resolution, pixel ratio, aspect ratio, colour depth and colour gamut. No install, nothing uploaded.
  2. Sharpness testBlurry text has three causes and none is the panel: chroma subsampling, non-native scaling, or BGR subpixels. Four patterns show which you have. In the browser.
  3. Dead pixel testFill your screen with solid colours and find dead, stuck or hot pixels. Runs in the browser, nothing to install.
  4. Backlight bleed testFill the screen with black and check the edges and corners for light leaking through. Tells backlight bleed apart from normal IPS glow.
  5. Screen uniformity testFlat grey fields at five levels show patches, bands, a dark corner or a colour tint — the dirty screen effect a black field hides and a panning shot reveals.
  6. Contrast testTwo ladders of near-black and near-white patches show whether your monitor clips blacks or highlights. Black crush and white clipping, checked free.
  7. RGB range testBlacks grey and washed out, or shadow detail gone? The signal and the screen disagree about 0-255 or 16-235. Three patterns say which, and how to fix it.
  8. Colour testSolid colours, stepped grey and RGB ramps to reveal banding, tinting and uneven colour on any screen. Runs in the browser.
  9. Refresh rate testMeasure the refresh rate your monitor is really running at, plus frame time and skipped frames. No install, results in three seconds.
  10. Motion blur testThree patterns at four speeds show how much a moving object smears on your screen, and whether a higher refresh rate would help. Runs in the browser.
  11. Ghosting testMoving blocks on fifteen grey-to-grey transitions show where your panel trails, and whether the fault is weak overdrive or overshoot. Runs in the browser.
  12. Flicker testFind out whether your monitor backlight is strobing. PWM flicker causes eye strain and headaches long before anyone notices it visually.
  13. Stuck pixel fixerFlash a movable square of rapidly changing colour over a stuck pixel to try to bring it back. Free, runs in the browser, nothing to install.

Keyboard

  1. Keyboard testPress each key and watch it light up. Finds dead keys, stuck keys, and keys reporting the wrong position. Works with any keyboard. Free, nothing to install.
  2. Key chatter testCheck whether a key registers twice from a single press. Measures the gap in milliseconds so you can tell a fault from fast typing.
  3. Key rollover testFind out how many keys your keyboard registers at once, where it drops them, and whether it ghosts — reports a key you never pressed. Free, in the browser.

Mouse

  1. Mouse testCheck every mouse button, both wheel directions and pointer movement. Free, runs in the browser, nothing to install.
  2. Mouse double click testFind out whether your mouse registers two clicks when you only made one. Measures the gap in milliseconds. Free, in the browser.
  3. Mouse wheel testTest your scroll wheel for the fault that makes pages jump the wrong way. Counts every notch that reports the wrong direction. Free, runs in the browser.
  4. Mouse polling rate testMeasure how many times a second your mouse reports its position. Free, runs in the browser.
  5. Click speed testMeasure how many times a second you can click. Ten seconds, starts on your first click. Free, in the browser.
  6. Input lag testMeasure how long your click takes to reach the page and reach a frame, in milliseconds — and read plainly which part of input lag a browser can and cannot see.

Microphone

  1. Microphone testSee your microphone level, watch the waveform and play back a recording. Runs in the browser, and nothing is ever uploaded.
  2. Background noise testMeasure how much room and hardware noise your microphone picks up, and how far your voice sits above it. Free, nothing uploaded.
  3. Echo testCheck whether your microphone is picking up your speakers, which is what makes other people hear their own voice back. Runs in the browser.
  4. Audio latency testMeasure real audio latency — the round trip from your speakers to your microphone, in milliseconds. Finds the delay Bluetooth adds. Nothing is uploaded.

Headphones and speakers

  1. Speaker and headphone testPlay sound through the left speaker, the right, or both, and find out whether a channel is dead, swapped or quiet. Free, in the browser.
  2. Polarity testFind out whether one of your speakers is wired backwards, which drains the bass and hollows out the middle. Free, runs in the browser.
  3. Frequency range testSweep from 20 Hz to 20 kHz and find where your headphones, speakers or hearing stop. Free, runs in the browser.
  4. Audio and video sync testA flash and a click on one beat. Slide the click until they land together and read the offset between picture and sound in ms. Finds Bluetooth and TV delay.

Webcam

  1. Webcam testSee your camera picture, its real resolution and frame rate, and take a still. Runs in the browser, and no image is ever uploaded.
  2. Webcam frame rate testCount the frames your camera really delivers, not the number it claims. Free, runs in the browser.

Phone

  1. Touchscreen testDrag a finger across the whole screen and find the areas that do not respond. Free, runs in the browser, nothing to install.
  2. Multi-touch testFind out how many simultaneous touches your screen registers, and whether it loses one. Free, in the browser.
  3. Phone sensor testCheck the tilt, motion and compass sensors in your phone with a live spirit level and readout. Free, in the browser.
  4. Vibration testTrigger a short buzz, a long one and a pattern to check the vibration motor in your phone. Free, in the browser.
  5. GPS testTest your phone GPS in the browser: watch the radius shrink, time the satellite fix, and tell a real fix from Wi-Fi positioning. Nothing is sent anywhere.

Controller

  1. Gamepad testTest every button, stick and trigger on any controller in the browser. Works with Xbox, PlayStation, Switch and generic pads. Nothing to install.
  2. Stick drift testMeasure controller stick drift as a percentage of full deflection, at rest and after the stick returns to centre. Tells you whether a dead zone will hide it.

Situations

  1. Bluetooth headphones delayedSound behind the picture on Bluetooth: measure the delay in ms, see how much is the link, and find which fix — codec, profile, player offset or cable — applies.
  2. Checking a used controller before you buyA used PlayStation, Xbox or Switch controller has one fault that matters — drift — and several that are cheap. Nine checks, expensive one first.
  3. Checking a used laptop before you buyA run through the screen, keyboard, camera, microphone and speakers of a second-hand laptop, and what each finding is worth off the asking price.
  4. Checking a used monitor before you buyTen minutes of tests that find the faults a used monitor hides, which are permanent, which are free to fix, and what each is worth off the price.
  5. Checking a used phone before you buyTen minutes on a second-hand phone: screen, touch, cameras, sound and sensors, plus the four checks that are not tests at all.
  6. Laptop keyboard not workingDead keys, a whole keyboard that types nothing, or letters that come out as digits. Nine steps that separate a setting from a repair.
  7. Monitor flickering or cutting outFlickering or blinking black? Three suspects — cable, graphics card, monitor. Eight steps, cheapest first, to name the right one before you buy anything.
  8. No sound on a MacSilence from the speakers, or from one app only. Ten checks that tell a macOS setting from broken hardware, cheapest first.
  9. No sound on Windows 11Silence from the speakers, or from one program only. Nine steps that separate a Windows 11 setting from broken hardware, cheapest first.
  10. Nobody can hear meWhy the mic works everywhere except the call: each app keeps its own device list, permission, a Bluetooth headset in music mode, level, processing.
  11. Second monitor not detectedA second screen that stays black or never appears in display settings. Nine steps that separate a cable from a setting, in the order they fail.
  12. Sound in one ear onlyWork out whether it is the plug, the pairing, the balance, wax in the mesh, the cable, or the headphones. Checks in the order that costs nothing first.
  13. Webcam not workingBlack picture, no camera found, or a webcam that works in one app and not another. Eight steps that separate a permission from a fault. Usually the permission.

Coming soon

  1. System and browser
  2. Network