# Keyboard Test > Free online keyboard tester — press each key and see it light up on a full visual keyboard. Detect dead or stuck keys, count presses, read key codes live, and test N-key rollover and ghosting. 100% in-browser, no download. Check that every key on your keyboard registers. Press keys and watch them light up on a full on-screen keyboard, track which keys you've tested, see the live key, event.code and keyCode, count presses per key, and measure N-key rollover by holding several keys at once. Everything is detected locally from your real keystrokes — nothing is uploaded. - **Live tool:** https://www.toolnova.org/diagnostics-tools/keyboard-test - **Category:** Speed Test & Diagnostics (https://www.toolnova.org/diagnostics-tools) - **Price:** Free - **Requirements:** Runs in a modern web browser · No signup · No install ## What this tool does - Full on-screen keyboard that highlights each key as you press it, in real time. - Coverage tracker showing exactly which keys you've tested and which remain untested. - Live readout of the key, KeyboardEvent.code and legacy keyCode for the last press. - Per-key press counters so you can spot double-firing or chattering switches. - N-key rollover / anti-ghosting test — hold multiple keys and see the maximum registered at once. - Layout-independent: uses event.code, so it works regardless of your language layout. - Save progress locally and reset anytime — no signup, nothing leaves your device. ## How to use Keyboard Test 1. **Click the page, then start pressing keys** — Make sure the page has focus, then press keys one at a time. Each key lights up blue while held and turns green once it's been tested. 2. **Watch the live readout** — The panels at the top show the last key you pressed along with its event.code and keyCode — handy for remapping or debugging. 3. **Fill the coverage bar** — Work across the whole keyboard until the coverage bar reaches 100%. Any key that never lights up is likely dead or not registering. 4. **Test N-key rollover** — Hold several keys down together (for example W + A + Shift + Space). The Max Rollover counter shows how many simultaneous keys your keyboard can report. 5. **Check counts and reset** — Use the per-key counters to catch a switch that fires twice on one press. Save your progress or reset to start a fresh test. ## Common use cases - Diagnosing a dead, stuck or unresponsive key before buying a replacement keyboard - Testing a newly bought or second-hand mechanical keyboard for faults - Checking for the double-typing / chatter fault on a worn key switch - Verifying N-key rollover and anti-ghosting on a gaming keyboard - Finding the exact event.code or keyCode of a key for remapping or development ## About ### Spotting dead keys and switch chatter A keyboard tester is the fastest way to confirm a hardware fault. Press every key and any that never light up on the on-screen layout aren't registering — a genuine dead key. The per-key press counters catch the opposite problem too: if a single physical press ever adds two to a key's count, that switch is 'chattering' (double-firing), a common fault on worn membrane and mechanical boards. Because the test reads your keystrokes directly through the browser, what you see is exactly what your operating system receives. ### What N-key rollover really means N-key rollover (NKRO) is how many keys your keyboard can register at the exact same time. Cheap membrane keyboards often cap at 2–3 simultaneous keys and then start 'ghosting' — dropping or inventing keypresses — which ruins fast typing and gaming combos like moving and jumping while shooting. Hold a cluster of keys and this tool's Max Rollover counter shows your board's real limit. Full-NKRO gaming keyboards will happily report six or more at once. ### Layout-independent and private The tester identifies keys by their physical position using KeyboardEvent.code, so it works the same whether your layout is QWERTY, AZERTY or Dvorak, and it shows the code and keyCode you'll need for remapping or web development. Everything runs locally in your browser — no keystrokes are logged or uploaded, which matters because you're pressing keys on your own machine. ## FAQ ### How do I test my keyboard online? Open this page, click it to give it focus, then press each key. Every key lights up on the on-screen keyboard as you press it and turns green once tested. Any key that never lights up isn't registering. It works instantly in your browser with nothing to install. ### How do I know if a key is dead? Press it and watch the on-screen keyboard. If the matching key doesn't light up and the coverage counter doesn't increase, that key isn't sending a signal — it's likely dead or disconnected. Try it a few times to be sure it isn't just a firm switch. ### What is N-key rollover and how do I test it? N-key rollover (NKRO) is how many keys your keyboard can register simultaneously. Hold several keys at once (e.g. W + A + Shift + Space) and check the Max Rollover counter. Basic keyboards often stop at 2–3 keys (causing 'ghosting'); gaming keyboards with full NKRO register six or more. ### Can this detect a key that types twice (chatter)? Yes. Each key has a press counter. If a single clean press ever increases a key's count by two, that switch is double-firing — a hardware fault called chatter, common on worn keyboards. The counters make it easy to spot. ### Does it work with any keyboard layout? Yes. The test identifies keys by physical position using KeyboardEvent.code, so it behaves the same on QWERTY, AZERTY, Dvorak and others. It also shows the key, code and keyCode, which is useful for remapping and development. ### Is my typing recorded? No. Everything runs locally in your browser to light up the keys and count presses — no keystrokes are logged, stored, or sent anywhere. You can optionally save your tested-keys progress locally on your own device. --- ToolNova — free, privacy-first browser tools. Most tools process data locally on your device. See https://www.toolnova.org/llms.txt for the full directory.