Online Keyboard Test
The test lights a map as it receives keyboard events, stores `KeyboardEvent.code`, measures system repeat intervals and counts simultaneous keys observed by the page.
Open tool fullscreen →Interface and local controls remain in Portuguese.
How to use
- Open the instrument: while it is active every MonitorSmith shortcut is disabled so nothing interferes with the reading.
- Press every key one by one; already registered keys keep an amber outline and the active key lights up solid.
- Hold combinations of three, four and six keys at once and watch the simultaneous counter to find your keyboard limit.
When to use
- Find dead or intermittent keys before buying or selling a used keyboard.
- Observe the interval of automatic key repeat configured by the system.
- Compare simultaneous combinations exposed to the browser without certifying physical NKRO.
- Inspect `KeyboardEvent.code` and `key` while investigating macros, games and remaps.
Limitations
Keys intercepted by the operating system or firmware — Print Screen, media keys, Fn and some Windows-key combinations — may never reach the browser, and that is not a defect.
Frequently Asked Questions
- One key does not light up. Is the keyboard faulty?
- Maybe, but the system, browser, firmware or a global shortcut may intercept it. Repeat in another application or device before assigning the symptom to hardware.
- How should I interpret the simultaneous-key counter?
- It shows the most events that reached the page for that combination. Try several combinations; the result cannot certify the entire matrix or keyboard protocol.
Technical Methodology & Display Science
The reading uses `keydown` and `keyup` events and records `KeyboardEvent.code`, a DOM identifier associated with an expected position, plus `key`, which reflects the layout-interpreted value. Neither is a raw device scan code.
Repeat interval is measured only on events with the repeat flag set, comparing performance.now() timestamps. That number matches the repeat rate configured in the operating system, not a hardware characteristic.
Simultaneous counting keeps a set of currently held events and records the largest size reached. The operating system, firmware, matrix, protocol and chosen combination can limit what reaches the page.