Keyboard tester

How to use the keyboard tester

Pick the layout that matches your keyboard, then press every key once. Each key turns green when your computer receives it, and blue while you hold it down. When the counter shows every key as tested, your keyboard works.

• Untested keys stay grey, so you can see at a glance which ones you missed or which ones failed.
• Last key shows the key name, its code and the old keyCode value. Developers and people setting up macros often need these.
• Held for shows how long the last key stayed down. Use it to check that a key releases cleanly and does not stick.
• In Chrome and Edge the labels follow your own keyboard language, so a Danish, German or French layout shows its own letters.

Some keys cannot be caught by any website. The Fn key never reaches the browser, and the system grabs a few shortcuts first, like the Windows key, Ctrl+Alt+Delete and Cmd+Tab. Print Screen only reports when you let go of it.

What to do when a key does not light up

A key that stays dark when you press it did not send anything to your computer. Work through these steps in order, and test again after each one.

1. Check the obvious locks. Num Lock changes what the number pad sends, and some laptops have an Fn Lock that swaps the top row between F1 to F12 and media keys. Press Fn together with the key if the top row does nothing.
2. Try a different port or cable. Plug a USB keyboard straight into the computer, not into a hub or monitor. For a wireless keyboard, charge it or replace the batteries, then reconnect the receiver or re-pair it over Bluetooth.
3. Clean under the key. Crumbs and dust are the most common cause of a single dead or sticky key. Turn the keyboard upside down and tap it, then use compressed air at an angle. On a mechanical keyboard you can pull the keycap off with a keycap puller and clean the switch.
4. Rule out software. Close remapping tools (like PowerToys Keyboard Manager or Karabiner on Mac), gaming software macros and accessibility features such as Filter Keys on Windows, which ignores short presses.
5. Test on another computer. If the same keys fail elsewhere, the keyboard is at fault. If they work, the problem sits in your system settings or drivers.

Windows

Open Device Manager, expand Keyboards, right-click your keyboard and choose Uninstall device, then restart. Windows installs the driver again. Also check Settings, Accessibility, Keyboard and turn off Sticky Keys and Filter Keys while you test.

Mac

Open System Settings, Keyboard, and check that the right input source is selected. For a Bluetooth keyboard, remove it under Bluetooth and pair it again. If the built-in MacBook keyboard fails, an SMC reset (on Intel Macs) or a full shutdown can clear it.

Key chatter and double presses

Chatter means one press registers as two or more. It is common on worn mechanical switches. The tester flags any key that fires again less than 35 ms after it was released, which is faster than a finger can press twice. If a key keeps chattering, cleaning the switch often helps. If not, the switch needs replacing, or you can raise the debounce time in your keyboard software if it has that setting.

Which layout should you pick?

Frequently asked questions

Short answers to the questions people ask most about this test.

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