EarChord

EarChord finds the chords in any song. Drop in an MP3, WAV, M4A, or AIFF file and it returns a timed chord progression, the key, and the BPM. It's free and unlimited, needs no account, and analyzes the audio in your browser, so the file never leaves your device. It detects major and minor triads, so use it to check your ear, not as a full transcription.