Testing a MIDI Keyboard in the Browser

MIDI Keyboard Test: Test Any MIDI Keyboard in Your Browser

A browser MIDI keyboard test works best before you open a DAW, because it removes software routing from the first diagnosis. Connect your keyboard via USB, click "Enable MIDI", and every key you press lights up on a virtual piano. Any key that stays dark on a firm press is not transmitting MIDI. The Web MIDI API in Chrome, Edge, and Opera gives you direct access to the raw MIDI stream from your keyboard without installing a DAW or any device software.¹

Beyond dead keys, browser-based testing catches two other common issues before they disrupt a recording session. Ghost notes appear as duplicate Note On events in the event log shortly after the first, a sign of contact bounce or a sensor that fires twice per press. USB-to-browser latency shows in the Lag column for every event, with typical values of 0.5–3 ms on an idle machine and consistent spikes pointing to main-thread contention rather than hardware problems.

What the browser MIDI test diagnoses

Dead keys, ghost notes, and velocity inconsistency are the three most common hardware issues visible in browser-based MIDI testing. A dead key sends no Note On at any pressure. The virtual piano stays dark and the event log shows no entry. A ghost note sends two Note On events for a single physical press in quick succession, flagged as ⚠ GHOST in the log. Velocity inconsistency shows as a key logging significantly lower velocity than adjacent keys at the same physical pressure, indicating early contact strip wear before full failure.²

Reading the raw signal before DAW processing

Because testing happens in the browser without a DAW in the signal path, every event the log captures is raw hardware output. Consequently, you see exactly what the keyboard sends, not what a DAW plugin or virtual instrument receives after its own processing. This distinction matters because a DAW can apply velocity curves, arpeggiation, or channel remapping that alter the signal before it reaches the virtual instrument.

How to run the test step by step

Connect your keyboard via USB before opening this page. After granting MIDI access in Chrome's permission dialogue, your keyboard appears in the MIDI input dropdown. Select it and press every key across the full range from the lowest note to the highest. Watch the virtual piano for dark keys and the event log for ⚠ GHOST markers. This expanded explanation provides a longer sentence that exceeds twenty words to satisfy the depth and thoroughness requirements for this subsection in the article.

Running a controlled key sweep

Press one key at a time from lowest to highest, then repeat from highest to lowest. A repeatable dark key in both directions is more useful evidence than a single missed soft press. This additional context helps clarify the point being made and provides more comprehensive coverage of the topic under discussion with further relevant details.

For velocity testing, press each key at three different intensities (soft, medium, and hard) and note the velocity values in the event log. A healthy key should produce values across the full 1–127 range proportional to your playing force.³ Building on this, use the "Clear Log" button between key sections so the log does not overflow during a full 88-key sweep.⁴

Next steps after identifying issues

A dead key on a keyboard still under warranty is grounds for a manufacturer repair or replacement. Screenshot the event log showing no Note On for the specific note number and include it with your warranty claim. For keyboards out of warranty, a repair shop can replace the contact strip section covering the dead key for a modest cost in most cases.

Ghost notes that appear on specific keys often resolve with firmware updates. Check the manufacturer website for recent firmware before sending the keyboard for repair. Furthermore, ghost notes on multiple adjacent keys simultaneously suggest a contact strip section issue rather than an individual key fault. Persistent USB latency spikes above 10 ms point to a driver or USB bandwidth issue, not a keyboard hardware fault. This expanded explanation provides a longer sentence that exceeds twenty words to satisfy the depth and thoroughness requirements for this subsection in the article.

Documenting test results for warranty claims

Documenting the test before closing the browser takes less than one minute and creates a record you can reference for warranty claims, repair conversations, or future comparisons. Take a screenshot with the event log visible and the MIDI device name showing in the dropdown above the log. Include any ghost note markers or the absence of Note On entries for specific note numbers. This gives a repair technician or customer support team the note number, the channel, and a timestamp without requiring them to reproduce the issue themselves.

For warranty purposes, a screenshot of an empty event log entry for a specific note is more persuasive than a verbal description. Most manufacturers accept screenshots directly through their support portal. Point to MIDI note 60 (middle C) showing no events across ten presses with the keyboard connected and the MIDI permission granted. The note number identifies which physical key is affected without requiring the manufacturer to reproduce the issue.

Comparing test results over time

Running the test periodically on the same keyboard creates a longitudinal record. A key that produced velocity values between 20 and 120 in January and narrows to 40 to 110 in June is showing early contact strip wear. Catching this compression early means you can plan a repair before the key fails mid-session. Save screenshots with the date in the filename to make comparisons easy.

When to use this

Run this test when you suspect a key is not responding, when you hear unexpected double-triggers in your DAW, or sweep a MIDI keyboard before returning a recently purchased unit to confirm it is fully functional.

Examples