Keyboard Tester Online: Test Windows, Mac & Laptop Keys

What to Check When Testing Your Keyboard

Work through the checks below to make sure every key and key combination on your keyboard registers correctly.

Check All Letter and Number Keys

Press every letter from A to Z and every number from 0 to 9, including the number row. Each key should light up on the virtual keyboard and stay highlighted as tested. If a key doesn't respond, the switch or membrane underneath is dead. If the wrong character appears, your OS is set to a different layout, like AZERTY or QWERTZ, instead of QWERTY.

Test Function Keys (F1 to F12)

Press F1 through F12 one at a time. If nothing registers, check for an Fn Lock or F Mode key. On most laptops, F1-F12 are bound to media controls by default, so you need to hold Fn or toggle Fn Lock to send the actual function key signal.

Test Modifier Keys (Shift, Ctrl, Alt, Cmd)

Modifiers have duplicates on the left and right sides, and Keyboard Tester detects each one separately. Press Left Shift and Right Shift individually, then do the same for Ctrl, Alt (and AltGr), and both Cmd or Windows keys. If only one side registers, that switch is faulty even if its twin works.

Check for Stuck or Repeating Keys

Watch the virtual keyboard with your hands off the keyboard. If any key stays lit or fires without a press, it's stuck. Debris under the keycap is the most common cause and is fixable with canned air or a keycap puller. Stuck keys after a liquid spill usually need the switch replaced.

Test for Keyboard Ghosting

Ghosting happens when you press three or more keys together, and some fail to register. Hold combinations like W + A + Shift + Space, or any three adjacent keys at once. Every key you press should light up. Keys that don't appear are being ghosted, which means the keyboard will drop inputs during gaming or fast typing.

Test N-Key Rollover (NKRO)

NKRO is the opposite of ghosting — the keyboard registers every simultaneous keypress. Most membrane keyboards support 2-6 key rollover; mechanical and gaming keyboards support full NKRO. Press as many keys at once as you can and count how many light up.

Verify the Spacebar, Enter, and Backspace

These are the most-pressed keys and fail first. Press the spacebar at its left, center, and right positions — stabilizer issues can cause one side to register while the other doesn't. Press Enter from both the main cluster and the numpad. Test Backspace repeatedly to confirm it doesn't double-fire or skip presses.

Test the Numpad and Navigation Cluster

Press every numpad key (0-9, operators, Enter, decimal) with Num Lock both on and off. Then test the navigation cluster: Insert, Home, Page Up, Delete, End, Page Down, and all four arrow keys.

How to Use the Keyboard Tester

Follow these four steps to check every key on your keyboard.

Step 1

Select Your Keyboard Layout

Choose the layout that matches your keyboard at the top of the tester. Pick Windows for a standard PC keyboard, Mac for an Apple or MacBook, or Mobile for on-screen phone and tablet testing. The virtual keyboard rearranges so every key on your device has a counterpart on screen.

Step 2

Press Any Key to Start

Click once inside the tester area to give it focus, then start pressing keys. Each key lights up with a ripple animation the moment you press it. Tested keys stay highlighted so you can see which ones you've checked and which are left.

Step 3

Watch the Key Press Log and Heatmap

The key press log records every keystroke along with its name and JavaScript event code. Toggle the heatmap to see which keys you press most often — color intensity grows with each press.

Step 4

Reset and Retest

Click the reset button to clear all tested keys and start over. Useful when testing multiple keyboards or running a clean second pass after fixing a stuck key or swapping a switch.

Why Your Key Might Not Be Working

If the tester shows a key responding, but it doesn't work in your apps, or if a key is completely dead, the cause is usually one of the issues below.

Hardware Failure or Worn-Out Switch

If the tester doesn't detect the press, the problem is physical. Mechanical switches are rated for 50-100 million presses, but heavily used keys (WASD, spacebar, Enter) wear out first. Membrane keyboards fail when the rubber dome or circuit tears. Replace the switch on a hot-swappable mechanical keyboard, or replace the whole keyboard for membrane and laptop models.

Debris or Dust Under the Keycap

A key that registers inconsistently or feels mushy usually has debris underneath. Turn the keyboard upside down and shake it gently, then use compressed air around the problem key. For stubborn debris, pop the keycap off with a keycap puller and clean the switch with a cotton swab dipped in isopropyl alcohol. Let it dry fully before reinstalling.

Fn Lock Is Accidentally Enabled

If F1-F12 aren't working the way you expect, Fn Lock is probably on. Look for an Fn Lock or F Mode key (often on Esc, Caps Lock, or one of the function keys) and press it to toggle. Some laptops require Fn + Esc or Fn + F Lock to switch between function keys and media shortcuts.

Wrong Keyboard Layout Selected in Your OS

If the key registers on the tester but types the wrong character in apps, your OS is set to a different layout. On Windows, go to Settings > Time & Language > Language & Region. On Mac, open System Settings > Keyboard > Input Sources. Remove any layout you don't use, like US International or AZERTY.

Outdated or Corrupted Keyboard Driver

Drivers can become corrupted after a Windows update or a sudden shutdown. Open Device Manager, expand Keyboards, right-click your keyboard, and select Uninstall device. Restart, and Windows reinstalls the driver automatically. For keyboards with custom software (Logitech, Razer, Corsair, SteelSeries), reinstall the latest version from the manufacturer's website.

Sticky Keys or Filter Keys are turned on

Sticky Keys hold modifier keys down for you; Filter Keys ignore brief or repeated presses. If keys are being skipped, dropped, or held when you don't want them to be, go to Settings > Accessibility > Keyboard on Windows and turn off Sticky Keys, Filter Keys, and Toggle Keys.

Software Conflict with Another App

Some apps intercept keyboard input before it reaches others. Macro software, game overlays, text expanders (TextExpander, AutoHotkey), remote desktop tools, and some antivirus programs can swallow keypresses. Close background apps one at a time to find the culprit, or boot into Safe Mode to test with minimal software loaded.

Liquid Damage or Corrosion

Keys may register right after a spill but start failing days later as corrosion spreads. For laptops, power off, remove the battery if possible, turn it upside down, and take it to a service center within 24 hours. For external keyboards, sticky sugary liquids usually cost more to clean than a budget replacement.

Frequently Asked Questions

Does the keyboard tester work on Mac or MacBook?

Yes. Switch the layout to Mac at the top of the tester, and the virtual keyboard matches the Apple layout, including Command, Option, and Fn keys.

Can I use this keyboard tester on a Chromebook?

Yes. It runs in Chrome on any Chromebook without installation. Use the Windows layout — most keys map directly, though the Launcher key replaces Caps Lock.

Does it work on Windows laptops and desktops?

Yes. Every Windows keyboard works, from 60% compact boards to full 104-key layouts with a numpad. Runs on Windows 10 and 11 in Chrome, Edge, and Firefox.

Can I test a laptop keyboard with this tool?

Yes. Press keys on your laptop and the virtual layout responds in real time. If F1-F12 are locked to media controls, hold Fn to test the actual function signals.

Does this work for mechanical keyboards and QMK or VIA builds?

Yes. Keyboard Tester detects left and right modifiers separately and shows the event code for each physical key position. Works with hot-swappable, soldered, and handwired builds.

Can I test a wireless or Bluetooth keyboard?

Yes. If it's paired and sending standard key events, every press registers. Delayed keys usually point to Bluetooth interference or a low battery, not a tester issue.

Do I need to download anything?

No. Keyboard Tester runs entirely in your browser. No install, no extension, no account. Once loaded, the tester even works offline.

Why is my key not working, but the tester shows it pressed?

The hardware is fine; the problem is the software. Usual causes: wrong keyboard layout in your OS, Sticky Keys enabled, a macro or remote desktop app intercepting input, or a corrupted driver.

What is keyboard ghosting?

Ghosting is when you press three or more keys at once, and some fail to register. It's a limit of cheaper keyboards. Test by holding W + A + Shift + Space. Keys that don't light up are being ghosted.

What is N-key rollover (NKRO)?

NKRO means every simultaneous keypress registers, no matter how many. Membrane keyboards usually support 2-6 keys; mechanical and gaming keyboards support full NKRO. Press multiple keys at once and count how many light up.

Why doesn't the Fn key show up on the tester?

Fn is handled at the hardware level on most laptops and doesn't send a standard event to the browser. This is normal. Test Fn by combining it with another key, like Fn + F5, and checking the result.

Why isn't Print Screen being detected?

Most browsers don't receive Print Screen because the OS intercepts it for screenshots. The same applies to Windows key combos and media keys. If the screenshot works, the key works.

How do I fix a stuck key?

Use compressed air first. If that fails, pull the keycap and clean the switch with isopropyl alcohol on a cotton swab. If it still sticks, the switch is worn and needs replacing.

Can I also test my mouse?

Not on this page. This tool is focused on keyboard testing only — key detection, ghosting, rollover, and modifier keys.

Are my keystrokes being recorded or sent anywhere?

No. All detection happens locally in your browser using the native KeyboardEvent API. Nothing is stored, logged, or sent to our servers. Close the tab, and everything is gone.

Keyboard Tester: Check Every Key Online, Instantly

All keys detected

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