Keyboard & Mouse Testing: How to Check Every Key and Button Without Software

Whether you just bought a new keyboard, suspect a key is sticking, or need to verify a mouse button is registering correctly — you don't need to download any software. Modern browsers expose keyboard and mouse events in full detail, which means a well-built browser tool can do everything a standalone tester can.

Here's how to use each tool and what to look for.

Keyboard Testing: Find Stuck, Missing, or Malfunctioning Keys

The most common keyboard problems are:

• Keys that don't register — the key feels fine physically but produces no character
• Keys that stick — sending repeated keydown events without being held
• Wrong keyCode — rare on modern keyboards but important for remapped layouts
• Modifier key issues — Ctrl, Shift, Alt, or Meta not triggering correctly

Our Keyboard Test tool shows a full visual keyboard layout. Press any key and it lights up:

• 🟢 Green — the key was pressed and released successfully
• 🟣 Purple — the key is currently held down
• ⬜ White — not yet tested

Reading the Key Info Panel

Every keypress displays eight data points:

Field	What it means
Key	The character produced (a, A, Enter, Space)
Code	The physical key location (KeyA, ShiftLeft, Space)
KeyCode	Legacy numeric code (still used by some apps)
Location	Standard / Left / Right / Numpad
Modifiers	Which Ctrl/Shift/Alt/Meta are held
Repeat	Yes if the key is being held and auto-repeating
Which	Legacy field, same as keyCode for most keys
Unicode	U+XXXX code point for printable characters

Key vs. Code: Key is layout-dependent (pressing the same physical key on AZERTY gives you a different character), while Code always refers to the physical position. If you're building a game or hotkey system, use Code.

Layout Switching

The tool supports three layouts:

• 🇺🇸 QWERTY — default US layout
• 🇫🇷 AZERTY — French layout (A and Q swapped, accented keys)
• 🇩🇪 QWERTZ — German/Central European (Y and Z swapped, umlauts)

Switch to the layout that matches your physical keyboard so the visual matches reality.

Exporting Results

After testing, click Export to download a .txt report listing every tested key, every untested key, and the full keypress history. Useful for support tickets or comparing two keyboards.

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Mouse Testing: Every Button, Every Scroll Direction

Mouse problems are trickier to diagnose because they're often intermittent. A button might work 95% of the time but double-click when you single-click, or a scroll wheel might skip positions. Our Mouse Test tool captures everything in real time.

What Gets Tested

Mouse Buttons (0–4):

Button	Name	Common use
0	Left	Primary click
1	Middle	Scroll click / open in new tab
2	Right	Context menu
3	Back	Browser back
4	Forward	Browser forward

Each button shows:

• Active state (colored, scaled down) while held
• Tested state (green outline) once released
• Click count — how many times it's been clicked

Scroll Wheel: The tool tracks both vertical and horizontal scroll delta. A faulty scroll wheel often shows irregular delta values (large jumps instead of smooth increments) that are invisible during normal use.

Click Map: The dark grid at the bottom records the last 50 click positions as colored dots — left (indigo), middle (amber), right (rose). Use this to verify click accuracy at different screen positions or to spot double-click issues (two dots appearing close together from a single click).

Common Mouse Faults and What They Look Like

Double-click fault: You click once but see two dots appear in the click map, or the click count jumps by 2.

Sticky button: The button stays in active (pressed) state after you release it — the colored background doesn't go away until you click again.

Scroll drift: The scroll Y value changes even when you haven't touched the scroll wheel.

Missing side buttons: Buttons 3 and 4 show no activity even when pressed — some systems don't pass these events to the browser.

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Typing Speed: Test the Keyboard Performance End-to-End

Once you've confirmed all keys register correctly, test real-world performance with our Typing Speed Test. This measures:

• WPM — words per minute
• Accuracy — percentage of correctly typed characters
• Errors — total incorrect keystrokes
• Time — configurable at 30s, 60s, or 120s

The test uses real English passages rather than random characters, which better reflects actual typing patterns. Aim for 40+ WPM for comfortable daily use; touch typists typically hit 70–100 WPM.

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Screen & Display: Confirm Your Setup is Right

Hardware testing isn't just about input devices. If you're setting up a new workstation or troubleshooting display issues, our Screen Resolution & Display Info tool shows:

• Screen resolution and viewport size
• Device pixel ratio (DPR) — useful for understanding retina/HiDPI displays
• Color depth
• Refresh rate
• Orientation

A DPR of 2 means your screen is rendering at double the logical pixels (retina display). If your DPR is 1 but you expected 2, your OS scaling settings may not be configured correctly.

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Quick Diagnostic Checklist

Use this checklist when diagnosing input device problems:

1. ✅ Open Keyboard Test and press every key systematically — Fn row first, then number row, then letter rows, then modifiers
2. ✅ Check the Untested keys section at the bottom — any keys still listed there after a full sweep are suspect
3. ✅ Hold down a key for 2 seconds and check Repeat: Yes — if it says No, auto-repeat may be disabled in your OS
4. ✅ Open Mouse Test and click every button including Back and Forward
5. ✅ Scroll slowly and watch the Scroll Y value — it should increase smoothly in small increments
6. ✅ Check the click map for phantom dots (extra clicks you didn't make)

For keyboards showing stuck keys or missed inputs that appeared after liquid exposure, testing while the keyboard is slightly tilted can confirm whether the issue is positional (liquid pooling).