Keyboard Tester — Check Keys, NKRO & Chatter Online
Detect dead keys, check N-key rollover, identify chatter, and practice typing speed. Real-time chord display with adjustable threshold. Works with all keyboards
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
- ✓Key press frequency heatmap — tracks which keys are pressed most often during typing practice, displayed as a color overlay on the keyboard layout
- ✓Switch debounce analysis — shows the millisecond gap between each key repeat event, helping mechanical keyboard enthusiasts fine-tune their keyboard's debounce settings
- ✓Click coordinate feedback — each key press displays a brief ripple animation on the keycap to confirm registration even when looking away from the screen
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
Frequently Asked Questions
Is this keyboard tester safe to use? Does it log my keystrokes?
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Completely safe. This tool runs entirely client-side in your browser using JavaScript's keyboard events. No keystroke data is ever transmitted to any server. Your key presses are only used to highlight the corresponding key on the visual layout and are never stored, logged, or transmitted outside your browser.
How is chatter detection different from the OS key repeat setting?
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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?
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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?
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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 resets — a visible gap in the rainbow confirms clean break contact.
What are 'Other Keys Detected' in the green badges?
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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?
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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 the typing practice track my input or store passages?
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No. The typing practice runs entirely in your browser — your typed text, WPM, and accuracy calculations stay in memory until you refresh or leave the page. Uploaded .txt files are read via FileReader and are never sent to a server. The built-in passage library consists of public-domain texts and original content.
Does this work with mechanical keyboards, gaming keyboards, and laptops?
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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?
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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?
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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.
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