Key detection API

Return musical key estimates your product can reason about.

Beatlyze analyzes tracks and returns key, scale, readable key notation, and key confidence as part of the completed JSON result.

Run demo track Get API key

Readable key notation such as Am plus underlying key and scale fieldsConfidence values for review and fallback logicBPM, LUFS, duration, and semantic hints in the same response

Submit

Upload a file or send a public URL.

Poll

Use the returned job ID.

Store

Save structured JSON in your product.

Example Beatlyze API

{
  "key": "A",
  "scale": "minor",
  "key_notation": "Am",
  "key_confidence": 0.88
}

Best fit

Use Beatlyze when the job is clear.

Use this page when harmonic matching, library organization, playlist rules, or catalog search needs machine-generated key metadata.

Key A

Underlying tonal center when detected.

Scale minor

Major/minor signal for harmonic workflows.

Notation Am

Human-readable output for UI and exports.

Confidence 0.88

Use it to separate automation from suggestions.

Workflows

Where this API earns its keep.

These are product workflows where Beatlyze can replace manual tagging, brittle scripts, or an internal audio worker backlog.

Workflow

Harmonic playlisting

Combine key and BPM to suggest compatible transitions or group tracks by musical movement.

Workflow

Catalog search

Expose key notation as a filter or facet for audio libraries that need musical metadata.

Workflow

Review routing

Treat low-confidence key output as a hint instead of writing uncertain metadata as fact.

Decision points

A practical API contract for product teams.

Beatlyze is intentionally explicit about lifecycle state, uncertainty, and integration boundaries.

Readable and machine-friendly

Beatlyze returns both normalized fields and display notation, so clients do not need to parse labels back into structure.

Honest uncertainty

Sparse, noisy, or non-tonal material can reduce confidence. The API makes that visible.

Pricing

Start free, then choose a monthly quota.

Evaluate the response shape with the demo and a free key. Paid tiers are for teams that need predictable monthly analysis volume.

Free

€0 / month

Test the result shape and run low-volume experiments.

50 analysis jobs each month
Upload and public URL analysis
Polling workflow
Anonymous URL demo available before signup

Get API key

Most practical start

Starter

€19 / month

For a first production integration with predictable usage.

2,000 analysis jobs each month
Batch URL submissions up to 10 items
Webhook delivery support
Usage and billing status endpoints

Pro

€49 / month

For production apps and recurring catalog workflows.

10,000 analysis jobs each month
Higher-volume API usage
Webhook delivery logs
Self-serve billing portal when configured

FAQ

Common questions before integration.

Short answers for developers deciding whether Beatlyze fits the product they are building.

What key fields are returned?

The result can include key, scale, key_notation, and key_confidence, alongside the rest of the audio metadata payload.

Is key detection suitable for fully automatic tagging?

It can be, but only when confidence is high enough for your product. Low-confidence results should stay advisory.

Can I use this with uploaded files?

Yes. Use POST /v1/analyze/upload with an API key, then poll the returned job ID.

Related buyer pages

Compare adjacent Beatlyze use cases.

Each page maps the same API surface to a different developer job-to-be-done.