Audio features API
for any track
BPM, key, energy, danceability, valence and 7 more features for nearly any track, even if no one has analyzed it before. Query by ISRC. If it's cached, you get features instantly. If audio can be found, we analyze it on-demand and cache it forever.
Works for nearly any track. Free tier. No credit card.
{ "data": { "isrc": "USRC17607839", "title": "Bohemian Rhapsody", "artist": "Queen", "features": { "bpm": 143.8, "key": "Bb", "energy": 0.72, "danceability": 0.39, "valence": 0.23, "acousticness": 0.28, "loudness": -7.2, "instrumentalness": 0.01, "time_signature": 4 } }}See it in action
Structured audio data,
one API call
Every response includes 12 audio features extracted by Essentia, the open-source audio analysis engine. Features are normalized 0 to 1 (BPM and loudness excepted). Cached permanently after first analysis.
Request
GET /v1/tracks/USRC17607839/features
Authorization: Bearer melo_sk_a1b2...Response: Audio Features
Bohemian Rhapsody
Queen
USRC17607839
143.8 BPM|Bb major
How it works
Three steps to audio data
Get your API key
Create a free account. Generate a key from the dashboard. No credit card, no approval process.
Query any track
Pass any ISRC. It doesn't matter if the track has been analyzed before. If it's cached, you get features instantly.
New track? Analyzed on the fly
Never-seen tracks return 202 (not billed). If audio can be found, we analyze it and cache the result forever. Retry in 30 seconds. Every future request is instant.
Analyze once, serve forever. The database grows with every request.
Built for developers
Everything you need from an audio API
12 Audio Features
BPM, key, energy, danceability, valence, acousticness, loudness, instrumentalness, speechiness, liveness, key confidence, and time signature.
3M+ Track Archive
Backed by the AcousticBrainz archive. Popular tracks are pre-cached. The database grows with every request.
On-Demand Analysis
Track not in the database? If audio can be found, we analyze it automatically and cache it forever. You never need to upload files.
Batch Operations
Look up 50 tracks at once. Or pre-analyze entire playlists for free with batch/analyze.
Similarity Recommendations
Find similar tracks by audio features. Seed up to 5 tracks and tune with target BPM, energy, danceability, and valence.
Fair Billing
202s, 429s, and 5xx responses are never billed. You only pay for successful lookups. Overage is opt-in at $0.002 per lookup.
Code examples
Works with any language
Standard REST API. Bearer token auth. JSON responses. If your language speaks HTTP, it works with MeloData.
The 202 retry pattern is the only thing to learn. When a track hasn't been analyzed yet, we return 202 with a Retry-After header. Wait, retry, and every future request for that track is an instant cache hit.
const API_KEY = process.env.MELODATA_API_KEY;
async function getFeatures(isrc) {
const res = await fetch(
`https://melodata.voltenworks.com/api/v1/tracks/${isrc}/features`,
{ headers: { Authorization: `Bearer ${API_KEY}` } }
);
// 202 = track is being analyzed (not billed)
if (res.status === 202) {
const wait = res.headers.get("Retry-After") || 30;
await new Promise(r => setTimeout(r, wait * 1000));
return getFeatures(isrc); // retry — cache hit
}
return res.json();
}
const { data } = await getFeatures("USRC17607839");
console.log(data.features.bpm); // 143.8
console.log(data.features.key); // "Bb"
Pricing
Start free, scale when you need to
All plans include every endpoint and feature. You choose how many lookups you need.
Free
Try it out
1,000 lookups / month
5 req/s, 100 req/min
- All endpoints
- All 12 audio features
- Batch operations
- No credit card
Dev
Perfect for building and testing
$160/yr billed annually
25,000 lookups / month
10 req/s, 300 req/min
- Everything in Free
- 25x more lookups
- Higher rate limits
- Email support
Pro
Built for production
$664/yr billed annually
200,000 lookups / month
25 req/s, 1,000 req/min
- Everything in Dev
- No polling, results via webhooks
- Track re-analysis
- Priority support
Scale
For high-volume production
$2512/yr billed annually
1,000,000 lookups / month
50 req/s, 3,000 req/min
- Everything in Pro
- SLA guarantee
- Dedicated support
- Custom overage rates
Need more? Enable overage billing at $0.002 per additional lookup. No surprises.
Get audio features for any track in seconds
Free tier. No credit card. Get your API key in seconds and make your first request in under a minute.
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