Specialized Diagnostic

MIDI Controller & Keyboard Tester

Test USB MIDI keyboards, drum pads, pitch bend, and CC knobs online for free. Monitor real-time MIDI note events, velocity (0–127), and hex packets.

Click 'Enable MIDI Access' to test USB MIDI keyboards & drum pads...

No MIDI Device Active

LAST MIDI NOTE --

NOTE VELOCITY (0-127) 0

CC MESSAGE / PITCH BEND 0

Live MIDI Event Stream

Click "Enable Web MIDI Access" above to begin monitoring real-time MIDI signals.

MIDI Signal & Velocity Benchmarks

Press keys across the entire piano register and test rotary encoders:

Linear Dynamic Velocity (1–127)

Soft keypresses register 15–40; firm strikes register 100–127. Natural acoustic velocity curve.

Velocity Compression

Output is clustered between 60 and 90 regardless of touch force. Adjust controller internal velocity curves.

Stuck Note / Velocity 127 Max

Key always triggers at 127 or fails to emit Note-OFF. Indicates dirty conductive rubber keybed contacts.

How to Get Started

Just three steps to run a complete controller test and understand your controller's health status.

Connect Controller

Connect your controller to your computer via USB cable or Bluetooth. If the browser doesn't respond, press any button on the controller to activate the connection.

Button Detection

Press each button in the visual interface and confirm the corresponding area lights up on screen. This helps troubleshoot unresponsive or double-clicking buttons.

Sticks & Vibration

Rotate the sticks to check linearity and drift issues; click the vibration test button to feel if the left and right motor feedback is working properly.

What would you like to do next?

Select a diagnostic calibration suite, deadzone analyzer, or high-frequency overclock tool.

Fix

Repair & Calibration

Calibrate zero-point offsets or follow step-by-step repair guides.

WebHID Calibration

Optimize

Game Deadzones

Calculate exact radial vs axial deadzone overlays for Fortnite, Apex, & COD.

Deadzone Calculator

Telemetry

Overclock & Circularity

Verify browser-observed update timing Hz stability and statistical circularity grades.

Hz & Circularity Tools

The Anatomy of MIDI Telemetry: Notes, Velocity & Control Change

The Musical Instrument Digital Interface (MIDI) standard serializes musical performance data into high-speed digital command packets transmitted at 31,250 baud over 5-pin DIN or full-speed USB endpoints.

3-Byte MIDI Packet Structure

Status Byte (Byte 1): Encodes the command type and MIDI channel (0–15). For example, 0x90 denotes Note ON on Channel 1, while 0xB0 denotes Control Change (CC).
Data Byte 1 (Byte 2): Defines the note number (0–127, where 60 represents Middle C / C4) or the CC parameter ID (CC 1 = Modulation, CC 7 = Volume, CC 64 = Sustain Pedal).
Data Byte 2 (Byte 3): Defines the strike velocity (0–127) or continuous parameter value. A Note ON with velocity 0 is treated as a Note OFF command.

Dual-Rubber Contact Keybed Mechanics

Unlike mechanical computer keyboards that use a single switch contact, velocity-sensitive MIDI keyboards (from Akai MPK, Novation Launchkey, Arturia KeyLab, and Native Instruments Komplete Kontrol) feature dual-height conductive rubber domes underneath each key. The onboard microcontroller measures the microsecond flight time between the upper contact closing and the lower contact bottoming out to calculate strike velocity.

Controller Hardware Glossary & Tips

Stick Drift & Deadzones

Stick drift occurs when analog sticks register input without being touched. This is typically caused by physical wear in traditional carbon-film potentiometers. A deadzone is a software-level threshold (e.g., 5-10%) applied to ignore these microscopic false inputs.

Hall Effect Sensors

Unlike traditional ALPS potentiometers, Hall Effect modules use magnetic fields to measure stick position. Because there is no physical contact or friction between the internal components, they are virtually immune to wear-induced stick drift, drastically extending the controller's lifespan.

Polling Rate (Hz) & Input Latency

Polling rate is how often your controller sends data to your device, measured in Hertz (Hz). A standard Bluetooth connection yields around 125Hz (8ms latency). Overclocking or using a wired USB connection can push this to 500Hz-1000Hz (1ms-2ms latency), critical for competitive gaming.

Circularity Error

When you rotate a joystick along its outer edge, a perfect module should trace a mathematically perfect circle. Circularity error measures the deviation from this perfect circle. High deviations (>15%) can result in uneven diagonal movement speeds in FPS games.

Frequently Asked Questions

Everything you need to know about testing your controller.

How do I test a USB MIDI keyboard or drum pad online?

Connect your USB or Bluetooth MIDI controller to your computer, click "Enable MIDI Access" above, and grant browser Web MIDI permissions. Press any key, drum pad, or knob. The real-time MIDI monitor displays incoming Note ON/OFF events, velocity levels (0–127), channel numbers, and raw hex bytes.

What MIDI messages does this online diagnostic tool monitor?

This tool monitors Note ON (0x90), Note OFF (0x80), Key Velocity (0–127), Continuous Controller messages (CC 0–127 like Modulation Wheel CC 1 and Expression CC 11), 14-Bit Pitch Bend (0–16383), Program Change, and Channel Aftertouch.

Which web browsers support Web MIDI API testing?

Google Chrome, Microsoft Edge, Opera, and Brave natively support the W3C Web MIDI API on Windows, macOS, Linux, and Android. (Apple Safari and Mozilla Firefox do not support Web MIDI).

Why do some keys on my MIDI keyboard play at maximum volume (127)?

When a key consistently outputs a static velocity of 127 regardless of how lightly you press, it indicates dirty or damaged dual-contact silicone rubber keybed switches underneath the piano key. Cleaning the contact carbon pills with 99% isopropyl alcohol restores velocity sensitivity.

Can I test wireless Bluetooth MIDI (BLE-MIDI) devices?

Yes. Pair your Bluetooth MIDI controller in your operating system settings (macOS Audio MIDI Setup or Windows Bluetooth settings), open this page in Chrome, and the device will enumerate automatically in the Web MIDI device list.

How this test works & its limits

This test reads your controller through the browser's standard Gamepad API — no drivers, no installs, nothing leaves your device.
Readings depend on connection mode: Bluetooth reports at lower rates than USB. Compare like-for-like (wired vs wired).
We measure the input reaching the browser — display lag and game-engine queues are outside this test's view.
A clean reading now does not guarantee no drift in-game: deadzones differ per game, and wear develops over time. Use the Drift Timeline to track yours.
This is a diagnostic, not a hardware-lab certification. For repair or RMA decisions, confirm with a second run or second tool.

Read the full methodology

100% Client-Side

All Gamepad API data stays in your browser. Zero tracking or data collection.

Instant Results

No downloads, plugins, or software installation needed. Works instantly.

Free Forever

No paywalls, subscription requirements, or hidden usage limits.