A good ear is the difference between a player who needs the tab and one who can hear a song and find it on the fretboard. This ear trainer is built for guitarists: every question is played on real string-and-fret positions through a guitar sound, not a piano tone, so what you hear in the exercise is what you hear when you pick up your instrument.
There are five kinds of question. Intervals play two notes and ask you how far apart they are. Chord quality strums a chord and asks whether it is major, minor, a seventh and so on. Play it back plays one note and listens through your microphone while you find it on your guitar. Scale type plays a scale shape and asks which scale it is. Chord progression plays a short sequence of chords and asks you to name the pattern, like I–IV–V.
Start on Easy, where the choices are few and the two notes always go upwards. Medium adds more intervals and both directions. Hard adds every interval, notes played together, and the full set of chord qualities and scales. A round is ten questions by default; at the end you see your score and where each question was played on the fretboard, so you can try the same positions yourself.
Use Advanced to change the direction, where on the neck the root notes are picked, the playback speed and the number of questions in a round. Your settings are kept on this device and you can share a link so a friend or student gets the exact same setup.