Ukulele Tuning API — Uke Tune Along Developer Documentation

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Overview

The Uke Tune Along API provides machine-readable tuning data for ukulele apps, practice reminders, educational tools, and automation workflows. It supports Standard GCEA, C♯, B, D, Low-A, Low-G, and Baritone DGBE tuning.

The API is public, requires no account or API key, and accepts GET requests. Microphone audio is not accepted or uploaded: the pitch-check endpoint works with a numeric frequency measured by your own application or device.

Base URL: https://uketunealong.com/api/v1

Interactive tuner: open the free Uke Tune Along tuner

Machine-readable specification: OpenAPI 3.1 document

List all tuning modes

curl "https://uketunealong.com/api/v1/tunings"

Use the optional a4 query parameter to select a reference pitch from 400 to 480 Hz. The default is A4 = 440 Hz.

curl "https://uketunealong.com/api/v1/tunings?a4=442"

Get one tuning mode

curl "https://uketunealong.com/api/v1/tunings/standard"
curl "https://uketunealong.com/api/v1/tunings/low-g"
curl "https://uketunealong.com/api/v1/tunings/baritone"

Each string includes its physical string number, scientific pitch notation, and target frequency. Strings are returned from the fourth string nearest the player's face to the first string nearest the floor.

{
  "apiVersion": "1.0.0",
  "instrument": "ukulele",
  "tuning": {
    "id": "standard",
    "name": "Standard GCEA",
    "referencePitch": { "note": "A4", "frequency": 440 },
    "strings": [
      { "number": 4, "note": "G4", "frequency": 391.995 },
      { "number": 3, "note": "C4", "frequency": 261.626 },
      { "number": 2, "note": "E4", "frequency": 329.628 },
      { "number": 1, "note": "A4", "frequency": 440 }
    ],
    "onlineTuner": "https://uketunealong.com/",
    "guide": "https://uketunealong.com/guides/ukulele-string-notes/"
  }
}

Available mode identifiers are standard, c-sharp, b-tuning, d-tuning, low-a, low-g, and baritone.

Check a measured pitch

Provide a measured frequency and target note:

curl "https://uketunealong.com/api/v1/pitch-check?frequency=435&target=A4"

Alternatively, identify the target by tuning mode and string number:

curl "https://uketunealong.com/api/v1/pitch-check?frequency=385&tuning=standard&string=4"

The result includes the difference in cents, a flat, sharp, or in_tune status, and a short adjustment instruction. A reading within five cents of the target is considered in tune.

{
  "apiVersion": "1.0.0",
  "inputFrequency": 435,
  "detectedNote": "A4",
  "target": { "note": "A4", "frequency": 440 },
  "referencePitch": { "note": "A4", "frequency": 440 },
  "cents": -19.79,
  "status": "flat",
  "inTune": false,
  "instruction": "Tighten the string slightly.",
  "onlineTuner": "https://uketunealong.com/"
}

Health check

curl "https://uketunealong.com/api/v1/health"

Use this endpoint to verify availability without downloading the full tuning list.

Use with n8n

Accept a tuning query with a GET Webhook, then use an HTTP Request node to call https://uketunealong.com/api/v1/tunings/standard (or the selected mode). Return the notes, frequencies, and tuner URL directly to the caller.

A useful workflow is: Webhook → HTTP Request → Prepare Query Result → Respond to Webhook. Users pass parameters such as ?tuning=low-g&a4=440. No schedule or messaging account is required. The webhook URL belongs to the workflow owner's n8n instance, separate from this API.

Errors and responsible use

Errors return a JSON error object with a stable code and readable message. Invalid parameters return HTTP 400, and unknown tuning modes return HTTP 404.

Responses allow cross-origin GET requests and may be cached. Please cache tuning data where practical and avoid unnecessary repeated requests. Availability is provided on a best-effort basis without a service-level agreement.