Discover / music.openverbs.com

Note parse

■ Challenge detected

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).

x402
Base
USDC

Listed price: $0.002
Challenge detected: 9 of the last 9 checks
Median response: 185 ms
Last checked: 16 Oct, 18:49 UTC
In our index since: 26 Sept 2026

Endpoint

curl -i https://music.openverbs.com/v1/note
# 402 Payment Required: pay with an x402 client (USDC on Base),
# then send the same request again with the payment attached.

5 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.openverbs.com/v1

POST/interval$0.002Name 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.
POST/chord$0.002Build 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.
POST/scale$0.002Build 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.
POST/note$0.002Parse 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).
POST/transpose$0.002Transpose a note by a (possibly negative) number of semitones. Result is spelled chromatically with sharps, or flats when `preferFlats` is true.

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

Showing 5 of 5 listed endpoints.

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

Recent checks

30 Sept 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.16 Oct 2026

All 9 checks

When (UTC)	Result	HTTP	Response
16 Oct, 18:49 UTC	Challenge detected	402	185ms
15 Oct, 11:37 UTC	Challenge detected	402	182ms
14 Oct, 00:19 UTC	Challenge detected	402	217ms
12 Oct, 00:34 UTC	Challenge detected	402	166ms
10 Oct, 10:04 UTC	Challenge detected	402	194ms
9 Oct, 03:33 UTC	Challenge detected	402	244ms
7 Oct, 21:31 UTC	Challenge detected	402	385ms
6 Oct, 16:01 UTC	Challenge detected	402	175ms
30 Sept, 05:03 UTC	Challenge detected	402	160ms

Questions

Did our last probe detect a payment challenge?

At our last probe on 16 Oct, 18:49 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 Note parse?

Its listed price is $0.002.

What payment terms does Note parse advertise?

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

Where is Note parse listed?

In x402 Bazaar. Superstables first indexed it on 26 Sept 2026.

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