{"x402Version":2,"name":"Music theory","description":"Music-theory primitives — parse notes and their frequency/MIDI number, name the interval between two notes, transpose, and build scales and chords with correct diatonic spelling. Standard pitch A4 = 440 Hz.","version":"0.1.0","openapi":"https://music.openverbs.com/openapi.json","resources":[{"url":"https://music.openverbs.com/v1/note","method":"POST","description":"Parse a note in scientific pitch notation (e.g. \"A4\", \"C#5\", \"Bb3\") into its letter, accidental, pitch class (0..11), octave, MIDI number and frequency in Hz (A4 = 440 Hz).","tags":["parse musical note","note frequency lookup","midi note converter","scientific pitch notation","musical note api","convert note to hz"],"accepts":[{"scheme":"exact","network":"eip155:8453","price":"$0.002","payTo":"0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A","asset":"USDC"}]},{"url":"https://music.openverbs.com/v1/interval","method":"POST","description":"Name the interval between two notes (`to` at or above `from`) — its size in semitones, its diatonic number and its quality (perfect/major/minor/augmented/diminished). Correct spelling matters: C→F# is an augmented fourth, C→Gb a diminished fifth.","tags":["music interval calculator","interval between notes","name musical interval","semitone interval lookup","diatonic interval api","compare two notes"],"accepts":[{"scheme":"exact","network":"eip155:8453","price":"$0.002","payTo":"0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A","asset":"USDC"}]},{"url":"https://music.openverbs.com/v1/transpose","method":"POST","description":"Transpose a note by a (possibly negative) number of semitones. Result is spelled chromatically with sharps, or flats when `preferFlats` is true.","tags":["transpose musical note","shift note by semitones","note transposition api","convert pitch up down","music key transpose","semitone transpose"],"accepts":[{"scheme":"exact","network":"eip155:8453","price":"$0.002","payTo":"0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A","asset":"USDC"}]},{"url":"https://music.openverbs.com/v1/scale","method":"POST","description":"Build a scale from a root note and type (major, natural-minor, harmonic-minor, melodic-minor, dorian, phrygian, lydian, mixolydian, locrian, major-pentatonic, minor-pentatonic, blues, chromatic). Heptatonic scales and modes are spelled diatonically (F major → F G A Bb C D E). Returns the note names, MIDI numbers and semitone intervals.","tags":["build music scale","scale notes generator","major scale api","musical mode builder","diatonic scale lookup","generate scale notes"],"accepts":[{"scheme":"exact","network":"eip155:8453","price":"$0.002","payTo":"0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A","asset":"USDC"}]},{"url":"https://music.openverbs.com/v1/chord","method":"POST","description":"Build a chord from a root note and quality (major, minor, dim, aug, maj7, min7, dom7, dim7, half-dim7, sus2, sus4, maj6, min6). Notes are spelled by stacked thirds (C dom7 → C E G Bb). Returns the note names, MIDI numbers and semitone intervals.","tags":["build music chord","chord notes generator","chord quality lookup","triad seventh chord api","generate chord tones","music chord builder"],"accepts":[{"scheme":"exact","network":"eip155:8453","price":"$0.002","payTo":"0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A","asset":"USDC"}]}]}