Free · in your phone's browser · no microphone
Tone generator
Tap Play and a clean A4 at 440 Hz starts. Type any frequency, pick any note, change the waveform or sweep from one pitch to another: the tone follows as you go.
440 Hz
A4
It starts quiet; turn it up slowly. On an iPhone, if you hear nothing, check the silent switch.
Sweep
What it does
It plays one pure tone from your browser, anywhere from 20 Hz to 20,000 Hz. Type the frequency, drag the slider, or pick a note and an octave: they stay in sync, and the readout says which note a frequency is nearest to and how many cents off (a hundred cents is a semitone). The buttons step a semitone (½) or an octave (8va) at a time.
The waveform changes the colour, not the pitch: a sine is the purest, a triangle a little brighter, square and saw are buzzy and full of overtones. A sweep glides from one frequency to another over the seconds you choose, evenly by octave, which is how you find a speaker's lowest note or a rattle in the room.
Tuning by ear? A4 = 440 Hz is the standard; some orchestras tune to 442, and 432 has its fans. Pick one and every note moves with it. If you'd rather have something listen to your instrument, use a tuner.
Look after your ears
A steady tone is more tiring than music at the same loudness. Start quiet, turn up slowly, keep high tones low and short, and stop if anything hurts or rings. Babies and pets hear differently: don't aim it at them.
Then make something of it
"Play it in a track" puts the note you were on into Brumm as a melody, inside a club track with a beat and a bass. No account, no upload: the note travels inside the link itself. Hum a whole line there, and it becomes an instrument.
No microphone here: the tone is made in your browser and nothing is sent anywhere. How the site counts visits.