The Interval Trainer drills note-to-note interval recognition across every standard interval — minor 2nd, major 2nd, minor 3rd, major 3rd, perfect 4th, tritone, perfect 5th, minor 6th, major 6th, minor 7th, and major 7th. Toggle the intervals you want to practice on the setup screen, then pick a direction.
Find the note — see a root and an interval (like "a minor third above F"), name the resulting note. The standard direction for sight-reading and constructing scales by ear.
Find the root — see a target note and an interval (like "B♭ is the perfect 4th of —"), name the root that sits below it. The reverse direction, which is what you need when reverse-engineering a chord, harmonizing a melody, or transposing a piece.
Practice with tap selectors for fast typing, music staff for sight-reading drills, piano keyboard with the prompt note highlighted in green as a visual anchor, or guitar fretboard for fretboard-position drilling.
Interval recognition is the bedrock skill for everything else in music theory. Chords are stacked intervals, scales are sequences of intervals, modulation is interval relationships. The faster you can name the third above any note, the faster you can do every other theory task. Best times stored locally; +20 seconds per wrong answer.