Online Keyboard Test: Double Typing, NKRO, Chatter & Speed

Online keyboard test for dead keys, N-key rollover, chatter, double typing and input latency. Test laptop and mechanical keyboards with real-time chord display.

Updated 2026-09-14

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Features

Real-time NKRO tracking: see exactly how many keys are pressed simultaneously with live chord/combo display and max NKRO counter
Chatter detection with adjustable threshold: distinguish OS key repeat from switch bounce via configurable gap timing
Break contact detection: identify intermittent key contact that triggers stray keydown events without a corresponding keyup
Long-press waveform visualization: rainbow gradient strip inside the keyboard case shows hold duration at ~60fps
Extra keys detection: media and special keys (volume, brightness, etc.) appear as green keycap-style badges
Win/Mac layout toggle: swaps Win/Alt/Ctrl labels between PC and Mac conventions without changing key positions
Typing practice with Free and Words modes: custom text or file open support, character-level accuracy, WPM tracking
Detailed key event log: unified scrollable panel with millisecond timestamps, event type, hold duration, and anomaly labels
Rollover visualization: the keyboard matrix lights up held keys in real time with distinct colors per key, making NKRO testing intuitive and visual
Real-time combo tracking: when 2+ keys are held at once, their names appear live on the NKRO card with a combo history log, verifying your keyboard's matrix wiring
Switch debounce analysis: shows the millisecond gap between each key repeat event, helping mechanical keyboard enthusiasts fine-tune their keyboard's debounce settings
Double typing diagnosis: hold a single key and inspect the event log gaps to distinguish OS repeat-rate settings from switch chatter hardware faults

How to Use

1Click anywhere on the page to focus the tester, then press any physical key; the keyboard lights up in real time.
2Watch the NKRO card at the top: the big blue number shows how many keys are held; held key names replace the subtitle when 2+ are pressed simultaneously.
3Adjust the chatter threshold slider to set the gap threshold (10–150ms): consecutive keydowns of the same key within this window are flagged as chatter (orange).
4Toggle between Win and Mac layout via the toggle; this swaps the labels on Win, Alt, and Ctrl keys for Mac users.
5Scroll to the Typing Practice section and choose Free mode for open-ended typing or Words mode for passage-based accuracy practice with custom text or .txt open.
6Use Reset to clear all pressed states, history, and stats; useful when switching to a different keyboard or starting a fresh test session.
7Run the typing practice in Free mode to evaluate real-world typing speed: type naturally and watch your WPM, accuracy, and character-level errors update live
8Upload a .txt file of a passage you need to practice typing: the Words mode loads your text and compares each character you type against the reference for precise accuracy tracking
9Test for key conflicts (ghosting): hold W, A, S, D, Shift, and Space together while watching the NKRO counter: if the count drops while keys are still held, the keyboard is hitting a rollover limit
10Diagnose repeated characters: press one key slowly and deliberately, once per press, then inspect the event log: a single press should log exactly one keydown; two keydowns without a keyup mean the switch is chattering

Frequently Asked Questions

How is chatter detection different from the OS key repeat setting?

The OS key repeat fires a sequence of keydown events with e.repeat = true once you hold a key beyond the OS repeat delay. This tool ignores e.repeat events entirely. Chatter detection measures the gap between consecutive non-repeat keydowns of the same physical key. If a key produces multiple keydowns without e.repeat within the threshold window, it's flagged as switch chatter, a hardware issue. You can adjust the threshold slider from 10ms to 150ms to tune sensitivity.

What is 'break contact' and how does the tool detect it?

Break contact (also called 'chatter on release') is when a key switch briefly re-closes during release, causing a stray keydown event without a matching keyup. The tool detects this by tracking held keys: if a keydown arrives for a key that's already being held down without an intervening keyup, it's flagged as break contact and highlighted in purple on the keyboard.

What do the colors on the waveform strip mean?

The rainbow gradient inside the keyboard case visualizes key hold duration in real time. Hue starts at green (120°) and cycles every ~1.5 seconds to red, purple, blue, and back to green. When you release all keys, the waveform shows a visible gap. A clean release with no stuck keys leaves a clear break in the rainbow.

What are 'Other Keys Detected' in the green badges?

These are keys that exist on your keyboard but aren't part of the standard 104-key layout: typically media keys (volume, play/pause), brightness controls, calculator, browser shortcuts, and other OEM-specific keys. They appear as green 3D-styled badges and help you verify that these extra keys are functioning.

What does the Win/Mac layout toggle do?

It swaps the labels on three modifier keys: Win → ⌘ Cmd, Alt → ⌥ Opt, Ctrl → ⌃ Ctrl. This helps Mac users who connect a PC keyboard visually match the legends on their keys. It does not remap the physical layout or change key positions; only the displayed labels change.

Does this work with mechanical keyboards, gaming keyboards, and laptops?

Yes. This tester works with any keyboard your operating system recognizes, including mechanical keyboards, membrane keyboards, gaming keyboards with macro keys, laptop built-in keyboards, and wireless Bluetooth keyboards. As long as the OS delivers keyboard events to the browser, the tester will detect them.

What NKRO (N-Key Rollover) means and how to test it?

NKRO means the keyboard can register any number of simultaneous key presses without ghosting or dropped inputs. Standard USB keyboards in boot protocol mode are limited to 6KRO (6 keys + modifiers). Gaming and mechanical keyboards usually support full NKRO over USB. To test: hold down multiple keys at once (try pressing all of W, A, S, D, Space, Shift, Ctrl simultaneously). The NKRO counter at the top shows the current simultaneous count. If keys drop out, the counter decreases, indicating a rollover limit.

What is keyboard chatter and how to fix it?

Chatter (switch bounce) occurs when a mechanical switch's contacts physically bounce on closing, registering multiple key presses from a single press. The tool detects this by measuring the gap between consecutive keydown events of the same key without an intervening keyup. If chatter is detected (orange indicator), try: 1) Adjust the chatter threshold lower; some switches naturally have faster bounce. 2) Clean the switch with contact cleaner. 3) For soldered keyboards, desolder and replace the faulty switch. 4) Some gaming keyboards allow adjusting debounce delay in their software; increase it to 4-8ms.

Why does my keyboard type double letters or repeat characters?

That is the user-visible symptom of switch chatter: a worn or dirty switch sends two signals from one press, so 'h' becomes 'hh'. Verify it here: press the offending key slowly, once per press, and watch the event log: if a second keydown appears without a keyup in between, the switch is chattering. First try cleaning the switch with contact cleaner and clicking it rapidly 30-50 times; if it still repeats, the switch needs replacement (soldered) or the keyboard is still under warranty.

Why don't some of my keys register in the keyboard tester?

The browser only receives standard keys. The Fn key is handled by keyboard firmware and never reaches the browser on any OS. Media keys (volume, brightness, play/pause) are sent as special scan codes that many laptops intercept at the driver level, so they often only work through the manufacturer's driver software. Some OS-level shortcuts (Ctrl+Alt+Del, Windows+L, Alt+Tab) are intercepted by the operating system before the page sees them. If a key works in normal typing but not here, check whether it is a standard key; if it does not work in normal typing either, the switch or its connection is faulty.

What is keyboard ghosting and how is it different from NKRO?

Ghosting is when the keyboard fails to register some keys because too many are pressed at once; the matrix design drops inputs to avoid false signals. NKRO (N-key rollover) means every key press registers no matter how many keys are held. Test it here: hold several keys at once (e.g. W, A, S, D, Shift, and Space) and watch the big counter: if the count drops while keys are still held, you're hitting a rollover limit (often 6KRO on budget keyboards). Ghosting is common on membrane keyboards; most mechanical and gaming keyboards support full NKRO or at least 6KRO without ghosting.

My keyboard repeats characters when I hold a key: is it hardware or Windows settings?

Both can cause repeats. Check Windows first: Settings → Devices → Typing → Advanced keyboard settings → Keyboard repeat delay and repeat rate. If repeat delay is very short or the repeat rate very fast, a held key will repeat characters quickly; that's the OS working as configured, not a fault. To rule out hardware: press the key slowly, once per press, and watch the event log: a single press should produce exactly one keydown. If you see a second keydown without a keyup in between, the switch is chattering (hardware). Test each suspect key three times; any keydown that repeats without a release points to switch wear.

Can I test a MacBook or Mac keyboard with this tool?

Yes, it works with any keyboard macOS delivers to the browser, including built-in MacBook keyboards, Magic Keyboards, and external PC keyboards. Use the Win/Mac layout toggle to relabel Win/Alt/Ctrl as Cmd/Opt/Ctrl. Two honest caveats: Fn keys are handled by firmware and never reach the browser, and macOS intercepts some shortcuts (Cmd+Tab, Cmd+Space, Control+Up) before the page sees them; neither means your keys are broken.

Can I measure my typing speed with this tester?

Yes. The Typing Practice section tracks words per minute (WPM), accuracy, and character-level errors live. Free mode measures your natural typing, Words mode compares against a reference passage (your own .txt or the built-in library) for precise accuracy. It is a browser-based estimate, not a certified typing exam; for formal tests use a dedicated typing test site.

Can this tester measure keyboard polling rate or latency?

No. A browser cannot measure either. Polling rate: a mouse reports position continuously, so coalesced pointer events reveal its report interval (125/500/1000 Hz are distinguishable in the mouse tester), but a keyboard only sends a report when a key changes (the event stream contains no device heartbeat), and on Windows the keyboard is claimed by the system's exclusive driver, so WebHID cannot open it either. Polling rate (125–8000 Hz) only affects how quickly the device itself processes input; browser key events arrive after the OS and driver have done their work. Latency: there is no physical reference point in a browser; measuring real keyboard latency requires a high-speed camera setup (record the keycap press and the character on screen, compare frames). What this page does measure: whether every key registers, rollover limits, chatter, and break contact, the most common keyboard faults.

Why is my keyboard tester online result unreliable in a browser?

Browsers only receive what the OS and keyboard driver expose: Fn, some media keys, and system-shortcut keys are filtered before reaching the page, and browser-level key repeat can mimic chatter. A browser keyboard tester is great for detecting chatter, dead keys, and ghosting on standard layouts, but for firmware-level diagnostics (polling rate, exact matrix behavior) use a dedicated desktop tool like Switch Hitter or Keyboard Tester Pro on Windows.

Does this tester work with magnetic Hall effect keyboards and Rapid Trigger?

Yes for key events, no for magnetic-specific settings: a Hall effect keyboard sends standard key events to the browser, so key registration, chatter, double typing, break contact and N-key rollover all test normally here. What you cannot test: actuation point adjustments (magnetic switches go down to 0.1 mm versus about 2 mm on mechanical switches) and Rapid Trigger, both of which live in the vendor driver (Wooting, DrunkDeer and similar). What you can still verify: an overly aggressive Rapid Trigger setting shows up in the event log as extra keydowns or keydowns without a keyup, the same signature as chatter, so you can confirm whether your RT parameters behave sanely.

How do I check whether every key on my keyboard works?

Press each key once on the on-screen keyboard: a lit key means it registered, and a full sweep finds every dead key in about a minute. This is how every keyboard checker works, and three passes make it thorough. First, press each key individually and confirm the highlight. Second, hold W, A, S, D, Shift and space together for a key-combination test and watch the rollover counter for drops. Third, reconcile the event log: a single press should record exactly one keydown, and any extra keydown is chatter. Fn and media keys are excluded: firmware and the OS intercept them before the browser sees them.

How do I test a laptop keyboard with this tool?

Laptop keyboards work with this tester just like external keyboards. Press each key to see it light up on the on-screen layout. The main limitation is the smaller key count: most laptop keyboards lack a numpad and have compressed arrow keys, but all standard keys register normally. Fn keys are handled by firmware and will not appear in the tester, which is a browser limitation, not a fault with your laptop. If some keys don't register, check whether they require a function key combination (Fn + key) at the hardware level.

How do I test a mechanical keyboard for chatter or dead switches?

Mechanical keyboards are ideal for this tester because each key has an independent switch. To test for chatter: press each key slowly and check the event log. A single press should log exactly one keydown. Two keydowns without a keyup means the switch is chattering. To find dead keys: sweep across all keys and watch the on-screen keyboard; any key that doesn't light up has a connection or switch problem. For a thorough test, also hold multiple keys at once to verify NKRO and check that no keys ghost (appear without being pressed).