Discover / music-theory.x402tookit.com

Music Theory

■ Challenge detected

Spell a chord from its symbol (Cmaj7, F#m7b5, G7b9, Dsus4, C/E): notes, intervals, semitones and MIDI numbers.

Listed price
$0.02
Challenge detected
1 of the last check
Median response
1402 ms
Last checked
21 Oct, 00:26 UTC
In our index since
21 Oct 2026

Endpoint

curl -i https://music-theory.x402tookit.com/chord
# 402 Payment Required: pay with an x402 client (USDC on Arbitrum),
# then send the same request again with the payment attached.
10 listed endpoints · on x402 Bazaar

Checks and payment terms on this page refer to the endpoint above. Other listed endpoints have not been checked individually.

Base URLhttps://music-theory.x402tookit.com

  • GET/freq-noteNo price listedFrequency in Hz to the nearest note, MIDI number and offset in cents; adjustable A4 reference; tuner-style result.
  • GET/chordNo price listedSpell a chord from its symbol (Cmaj7, F#m7b5, G7b9, Dsus4, C/E): notes, intervals, semitones and MIDI numbers.
  • GET/scaleNo price listedSpell a scale or mode on any root: major, minor, modes, harmonic and melodic minor, pentatonic, blues, whole tone.
  • GET/transposeNo price listedTranspose a chord progression by semitones or from one key to another, with spelling that fits the target key.
  • GET/intervalNo price listedInterval between two notes (quality, number, semitones) or the note a given interval above or below a note.
  • GET/key-signatureNo price listedKey signature (sharps or flats), circle-of-fifths neighbours, relative and parallel keys for any major or minor key.
  • GET/note-freqNo price listedNote name (C#4, Bb3) or MIDI number to MIDI, frequency in Hz and wavelength, with adjustable A4 reference pitch.
  • GET/tempoNo price listedBPM to milliseconds for note values, dotted and triplet delay times; or average tap intervals into a steady BPM.
  • GET/roman-numeralsNo price listedRoman numeral analysis of a chord progression in a key: numerals, inversions, borrowed chords, secondary dominants.
  • GET/chord-nameNo price listedName a chord from its notes (C E G Bb, A C E G): best name, inversion and alternative names; first note is the bass.

A dash means the listing gives no price or method. Copy buttons copy the full URL.

Showing 10 of 10 listed endpoints.

Agents can find it through the Superstables MCP server and JSON API: GET /api/v1/services/music-theory.x402tookit.com

Recent checks

21 Oct 2026One bar per check, showing up to 20 recent checks. Coloured bars show relative response time, with a minimum visible height; full-height grey bars mean no challenge was detected. “Challenge detected” means HTTP 402 or another detected payment-challenge signal.21 Oct 2026
All 1 checks
When (UTC)ResultHTTPResponse
21 Oct, 00:26 UTCChallenge detected4021402ms

Questions

Did our last probe detect a payment challenge?

At our last probe on 21 Oct, 00:26 UTC, it returned HTTP 402 or another detected payment-challenge signal. This check did not test payment, delivery or compatibility with the Superstables client.

What price is recorded for Music Theory?

Its listed price is $0.02.

What payment terms does Music Theory advertise?

The listing advertises x402, Arbitrum, Base, Polygon, Solana and USDC. It names cdp as its facilitator. Check the seller's current payment challenge and authentication requirements before paying.

Where is Music Theory listed?

In x402 Bazaar. Superstables first indexed it on 21 Oct 2026.

Something wrong on this page? Tell us.

Music Theory: listed price $0.02, x402 on Arbitrum, Base, Polygon and Solana