If the music is playing now
Press Listen to music and hold your device near the sound. HumFinder listens for up to twelve seconds. Only a fingerprint of the sound leaves your device, never the recording.
If the music has stopped
Press Hum a tune and hum what you remember. You will get a list of the closest songs to check by ear.
What it can recognize
It recognizes songs in its catalogue, which is mostly independent releases for now. When it doesn't know a song it says so, instead of guessing a wrong one.