Key & BPM Extraction

Python

import requests

url = "https://api.musicgpt.com/api/public/v1/extract_key_bpm"

headers = {
    "Authorization": "<API_KEY>"
}

data = {
    "webhook_url": "https://example.com/my-webhook"
}

# Option 1: audio_url
data["audio_url"] = "<YOUR_AUDIO_URL>"
response = requests.post(url, headers=headers, data=data)

# Option 2: File Upload
# with open("song.mp3", "rb") as f:
#     files = {"audio_file": f}
#     response = requests.post(url, headers=headers, data=data, files=files)

print(response.json())

curl --request POST \
  --url https://api.musicgpt.com/api/public/v1/extract_key_bpm \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: multipart/form-data' \
  --form 'audio_url=https://www.youtube.com/watch?v=example123' \
  --form 'audio_file=<string>' \
  --form webhook_url=http://your-webhook-url.com/callback \
  --form 0.audio_file='@example-file' \
  --form 1.audio_file='@example-file'

const form = new FormData();
form.append('audio_url', 'https://www.youtube.com/watch?v=example123');
form.append('audio_file', '<string>');
form.append('webhook_url', 'http://your-webhook-url.com/callback');
form.append('0.audio_file', '{
  "fileName": "example-file"
}');
form.append('1.audio_file', '{
  "fileName": "example-file"
}');

const options = {method: 'POST', headers: {Authorization: '<api-key>'}};

options.body = form;

fetch('https://api.musicgpt.com/api/public/v1/extract_key_bpm', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.musicgpt.com/api/public/v1/extract_key_bpm",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--",
  CURLOPT_HTTPHEADER => [
    "Authorization: <api-key>",
    "Content-Type: multipart/form-data; boundary=---011000010111000001101001"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.musicgpt.com/api/public/v1/extract_key_bpm"

	payload := strings.NewReader("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "<api-key>")
	req.Header.Add("Content-Type", "multipart/form-data; boundary=---011000010111000001101001")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.musicgpt.com/api/public/v1/extract_key_bpm")
  .header("Authorization", "<api-key>")
  .header("Content-Type", "multipart/form-data; boundary=---011000010111000001101001")
  .body("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.musicgpt.com/api/public/v1/extract_key_bpm")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = '<api-key>'
request["Content-Type"] = 'multipart/form-data; boundary=---011000010111000001101001'
request.body = "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--"

response = http.request(request)
puts response.read_body

{
  "success": true,
  "task_id": "keybpm789",
  "conversion_id": "conv456",
  "eta": -1,
  "credit_estimate": 100.1,
  "message": "Successfully published to queue"
}

{
  "success": false,
  "error": "Either audio_url or audio_file must be provided."
}

{
  "success": false,
  "error": "Internal Server Error"
}

POST

extract_key_bpm

Python

import requests

url = "https://api.musicgpt.com/api/public/v1/extract_key_bpm"

headers = {
    "Authorization": "<API_KEY>"
}

data = {
    "webhook_url": "https://example.com/my-webhook"
}

# Option 1: audio_url
data["audio_url"] = "<YOUR_AUDIO_URL>"
response = requests.post(url, headers=headers, data=data)

# Option 2: File Upload
# with open("song.mp3", "rb") as f:
#     files = {"audio_file": f}
#     response = requests.post(url, headers=headers, data=data, files=files)

print(response.json())

curl --request POST \
  --url https://api.musicgpt.com/api/public/v1/extract_key_bpm \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: multipart/form-data' \
  --form 'audio_url=https://www.youtube.com/watch?v=example123' \
  --form 'audio_file=<string>' \
  --form webhook_url=http://your-webhook-url.com/callback \
  --form 0.audio_file='@example-file' \
  --form 1.audio_file='@example-file'

const form = new FormData();
form.append('audio_url', 'https://www.youtube.com/watch?v=example123');
form.append('audio_file', '<string>');
form.append('webhook_url', 'http://your-webhook-url.com/callback');
form.append('0.audio_file', '{
  "fileName": "example-file"
}');
form.append('1.audio_file', '{
  "fileName": "example-file"
}');

const options = {method: 'POST', headers: {Authorization: '<api-key>'}};

options.body = form;

fetch('https://api.musicgpt.com/api/public/v1/extract_key_bpm', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.musicgpt.com/api/public/v1/extract_key_bpm",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--",
  CURLOPT_HTTPHEADER => [
    "Authorization: <api-key>",
    "Content-Type: multipart/form-data; boundary=---011000010111000001101001"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.musicgpt.com/api/public/v1/extract_key_bpm"

	payload := strings.NewReader("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "<api-key>")
	req.Header.Add("Content-Type", "multipart/form-data; boundary=---011000010111000001101001")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.musicgpt.com/api/public/v1/extract_key_bpm")
  .header("Authorization", "<api-key>")
  .header("Content-Type", "multipart/form-data; boundary=---011000010111000001101001")
  .body("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.musicgpt.com/api/public/v1/extract_key_bpm")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = '<api-key>'
request["Content-Type"] = 'multipart/form-data; boundary=---011000010111000001101001'
request.body = "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_url\"\r\n\r\nhttps://www.youtube.com/watch?v=example123\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"audio_file\"\r\n\r\n<string>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webhook_url\"\r\n\r\nhttp://your-webhook-url.com/callback\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"0.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"1.audio_file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n{\r\n  \"fileName\": \"example-file\"\r\n}\r\n-----011000010111000001101001--"

response = http.request(request)
puts response.read_body

{
  "success": true,
  "task_id": "keybpm789",
  "conversion_id": "conv456",
  "eta": -1,
  "credit_estimate": 100.1,
  "message": "Successfully published to queue"
}

{
  "success": false,
  "error": "Either audio_url or audio_file must be provided."
}

{
  "success": false,
  "error": "Internal Server Error"
}

Extract key and BPM (beats per minute) from an input audio file with optional webhook callback for asynchronous updates.

Endpoint

POST /v1/extract_key_bpm

This endpoint analyzes an audio file to determine its musical key and BPM. You can upload the audio file or provide a URL. Optionally, supply a webhook_url to receive asynchronous results.

Request Parameters

Parameter	Type	Required	Description
`audio_url`	`String`	Optional	The URL of an audio file to analyze. Either `audio_url` or `audio_file` must be provided.
`audio_file`	`UploadFile`	Optional	Upload the audio file directly. Either `audio_url` or `audio_file` must be provided.
`webhook_url`	`String`	Optional	Callback URL for async response.

💡 Note: Either audio_url or audio_file must be provided — one is required.

content-type: multipart/form-data

Sample Request

cURL

curl -X POST "https://api.musicgpt.com/api/public/v1/KeyBpmExtract" \
-H "accept: application/json" \
-H "Authorization: <api_key>" \
-F "audio_url=https://www.youtube.com/watch?v=jGflUbPQfW8" \
-F "webhook_url=http://webhook.musicgpt.com"

Python

import requests

url = "https://api.musicgpt.com/api/public/v1/extract_key_bpm"
headers = {
    "Authorization": "<<<api key>>>"
}

# Option 1: URL
payload = {
    "audio_url": "https://example.com/audio.m4a",
    "webhook_url": ""
}
response = requests.post(url, headers=headers, data=payload)
print(response.json())

# Option 2: File Upload
# payload = {
#     "webhook_url": "https://www.test.requestcatcher.com/test"
# }
# with open("audio.m4a", "rb") as f:
#     files = {"audio_file": f}
#     response = requests.post(url, headers=headers, data=payload, files=files)
# print(response.json())

🔐 Replace {path_to_your_audio_file}, api_key, and webhook_url before executing.

Sample Response

Success (200 OK)

{
  "success":true,
  "task_id":"69ec90f0-a00a-48f8-bdb3-8728a635e057",
  "conversion_id":"8be8c439-dbc9-4ae6-8fe3-3fcb95f5a60a",
  "eta":-1,
  "credit_estimate":0.48,
  "message":"Successfully Published to Queue",
  "status":"IN_QUEUE"
}

Common Errors

422 Unprocessable Entity: Both audio_url and audio_file cannot be None.
500 Internal Server Error: A server error occurred during processing.

Webhook Response

Once key and BPM extraction is completed, the webhook receives:

{
  "success": true, 
  "task_id": "69ec90f0-a00a-48f8-bdb3-8728a635e057", 
  "conversion_id": "8be8c439-dbc9-4ae6-8fe3-3fcb95f5a60a", 
  "conversion_path": "files/a4037db1-d163-48b3-b1ba-cb93c2045228.wav", 
  "conversion_duration": "0", 
  "key_changes": {"0-120": ["A# major"], "120-140": ["D# major", "G minor"], "140-220": ["A# major", "A# minor"]}, 
  "dominant_key": "A# major", 
  "bpm": 162, 
  "conversion_type": "Key BPM Extraction"
}

Output Fields

key_changes: A mapping of time ranges to identified keys.
dominant_key: The most prominent key throughout the audio.
bpm: Estimated beats per minute.
conversion_path: Path to the original input audio file.
conversion_path_wav: Path to the .wav version of the input file.

Payload and Request Formation

Authorizations

Authorization

string

header

required

Body

multipart/form-data

Option 1
Option 2

audio_url

string

required

Input audio URL (supported format: YouTube URL).

Example:

"https://www.youtube.com/watch?v=example123"

audio_file

file

Audio file to upload and process directly.

webhook_url

string

Callback URL for async processing results.

Example:

"http://your-webhook-url.com/callback"

Response

Successfully initiated key/bpm extraction

success

boolean

task_id

string

conversion_id

string

eta

integer

credit_estimate

number<float>

message

string

API Documentation

Utilities

Resources

Keep in mind

Features

Sample Request Endpoints

Helper Endpoints

Conversion Endpoints

Endpoint

Request Parameters

Sample Request

cURL

Python

Sample Response

Success (200 OK)

Common Errors

Webhook Response

Output Fields

Payload and Request Formation

Authorizations

Body

Response

​Endpoint

​Request Parameters

​Sample Request

​cURL

​Python

​Sample Response

​Success (200 OK)

​Common Errors

​Webhook Response

​Output Fields

​Payload and Request Formation

Authorizations

Body

Response

Endpoint

Request Parameters

Sample Request

cURL

Python

Sample Response

Success (200 OK)

Common Errors

Webhook Response

Output Fields

Payload and Request Formation