Online Keyboard Synth- 1 · InputPress a keyA controller sends MIDI note and velocity data.
- 2 · Sound engineAn instrument plays itThe receiving synth uses its selected sound.
- 3 · Audio outputYou hear the soundAudio goes to speakers or headphones.
MIDI, controllers, and synthesizers compared
A device can fill more than one role. A synthesizer with keys and MIDI output can play its own sounds and control a separate software instrument.
| Term | Its job | To hear it |
|---|---|---|
| MIDI | Performance and control data, including notes and velocity. | A receiving sound engine must turn note data into audio. |
| MIDI controller | Keys, pads, or controls that send messages. | If it has no built-in sounds, connect it to an instrument or app. |
| Hardware synthesizer | A physical instrument that generates and shapes sound; keys are optional. | Power, a way to play notes, and a suitable audio output to speakers or headphones. |
| Software synthesizer | A sound engine running in an app, a compatible host, or a browser. | The host or browser must run it and route audio to your listening output. |
| Digital piano or keyboard | A keyboard instrument that may combine built-in tones and MIDI control. | Check the model's sound engine, speakers, and audio connections. |
The MIDI Association's overview explains how messages describe a performance and how the receiving instrument interprets them.
Which setup do you need?
- Just want to play a few notes? Open the browser synth and click or tap a key. No MIDI device is required.
- Already have a MIDI controller? Check that your operating system recognizes it, then follow the MIDI connection steps in a supporting browser. The browser synth supplies the sound.
- Want to hear your hardware keyboard's own sounds? Use its speakers or the audio output specified in its manual. MIDI alone does not carry those sounds to this site.
- Want to practice with computer keys? Use the computer keyboard note map and exercises. This input works without a MIDI controller.
USB MIDI and USB audio are separate capabilities. A single cable may support both, depending on the instrument. Check its manual rather than assuming USB means audio. Yamaha's connection guide, for example, distinguishes MIDI transfer from model-dependent USB audio.
What MIDI does on this site
Online Keyboard Synth is a browser sound engine. Its oscillators, filter, and envelope generate the audio you hear; your MIDI keyboard supplies the performance input.
- Notes and playing strength
- Incoming Note On/Off messages start and release notes. Velocity controls playing strength. For example, a Note On for C4 with velocity 96 asks the synth to play that note with its selected sound; it contains no recorded audio.
- Sustain pedal
- Control Change 64 controls sustain. Your device must send that MIDI message for its pedal to work here.
- One shared sound
- Connected inputs play the same selected synth sound. There is no separate instrument assignment by MIDI channel.
- Other controls and outputs
- Pitch bend, aftertouch, program changes, and other controller messages are not mapped here. The site does not send MIDI to external instruments or capture their audio.
- Recording
- Record captures the browser synth's audio. You can download the original recording in the format your browser provides and convert it to WAV. These are audio recordings, not editable
.midfiles.
MIDI access needs a supporting browser, a secure connection, and permission. Support can also be restricted by the system or browser policy. See MDN's Web MIDI access requirements. The MIDI guide shows connection and sound status separately.
Connected, but still silent?
- Try a screen key first. If that is silent too, check the synth volume, device audio output, and browser sound permissions. Use the sound recovery action shown by the synth.
- If screen keys work, check the MIDI input. Confirm that the system recognizes your device, then use Connect MIDI. Read the connection status: unsupported, blocked access, and no detected input need different fixes in the MIDI troubleshooting guide.
- If notes work but a knob or wheel does not, check the supported controls above. An unmapped message will not change this synth. Choose the sound and adjust its controls on screen.
Frequently asked questions
Can a MIDI keyboard make sound on its own?
A controller without a built-in sound engine needs a receiving instrument or app to make sound. Some keyboards combine MIDI control with their own sounds. Check your model's manual for built-in tones and audio outputs; MIDI support alone does not establish either feature.
Do I need a synthesizer to use MIDI?
To hear MIDI notes, you need a sound source, such as a software instrument, hardware synthesizer, or sound module. You do not need to buy a separate hardware synth to use this site's browser instrument. MIDI also has control uses that do not produce sound. Check the browser MIDI connection steps
Is a synthesizer a keyboard?
A synthesizer generates and shapes sound. It can be a keyboard instrument, a module without keys, or software running on a computer or in a browser. Software needs a compatible host or browser; a hardware module still needs a way to trigger notes and hear its audio output.
Does a USB MIDI connection carry my keyboard's own sound?
MIDI messages do not contain the keyboard's audio. Some instruments also support USB audio over the same cable, but that is a separate capability to check in the model's manual. This site uses incoming MIDI to play its own synth; it does not capture your keyboard's USB audio or onboard sounds.
Can I try the synth without a MIDI keyboard?
Yes. Click or tap the screen keys, or use your computer keyboard on the synth page. A compatible MIDI device is optional and needs a supporting browser, operating-system recognition, and permission. Recordings made here are audio, not editable MIDI files. Play the browser synth