Bar / measure duration
API · /tempo-api
Tempo & BPM API
healthy
3,054 Subscribers
Musical timing maths as an API — turn a tempo into exact times. The durations endpoint gives the length of every note value (whole down to sixty-fourth, plus dotted and triplet variants) at a given BPM, in milliseconds, in hertz, and in samples at your sample rate. The delay endpoint is the producer's note-to-millisecond tool: the delay and reverb times for 1/1 to 1/32 (straight, dotted and triplet) so time-based effects lock to the tempo. The bar endpoint gives the duration of a bar for any time signature. The convert endpoint turns BPM into milliseconds per beat (and back) and names the Italian tempo marking — Largo, Adagio, Andante, Moderato, Allegro, Presto and the rest. Everything is computed locally and deterministically, so it is instant and private. Ideal for DAWs and music-production tools, drum machines and sequencers, delay and echo plug-ins, metronomes, and audio apps. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. This is tempo and rhythm timing; for notes, intervals, chords and scales use a music-theory API.
api.oanor.com/tempo-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 84 ms
- Server probes · 24h
- Subscribers
- 3,054
- active
- Total calls
- 70
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 7,735 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- 7,735 calls/month
- 2 req/sec
- Durations + delay + bar + convert
- No credit card
Starter
€9.25 /month
- 17,250 calls / month
- 8 requests / second
- Hard cap (429 above quota, no overage)
- 17.25k calls/month
- 8 req/sec
- ms / Hz / samples
- Email support
Pro
€29.15 /month
- 223,500 calls / month
- 20 requests / second
- Hard cap (429 above quota, no overage)
- 223.5k calls/month
- 20 req/sec
- DAW / plug-in pipelines
- Priority support
Mega
€67.15 /month
- 1,160,000 calls / month
- 50 requests / second
- Hard cap (429 above quota, no overage)
- 1.16M calls/month
- 50 req/sec
- Platform scale
- Dedicated SLA
Built by
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api.oanor.com/vinyl-api
Helmholtz Resonator API
Helmholtz-resonator acoustics as an API, computed locally and deterministically. The frequency endpoint computes the resonant frequency of a Helmholtz resonator — a cavity with a neck, like a bottle or a ported speaker box — from the neck area (or diameter), the neck length and the cavity volume, f = (c/2π)·√(A/(V·L_eff)), adding the acoustic end correction (about 0.85·radius for a flanged end and 0.61·radius for a free end) so a short or open neck resonates lower than its physical length suggests. The design endpoint inverts the relation, V = A·c²/(L_eff·ω²), to give the cavity volume needed to tune a resonator or a muffler chamber to a target frequency. The port-tuning endpoint sizes a bass-reflex (vented loudspeaker) box port in practical audio units — from the box volume in litres and the port diameter in centimetres it gives the tuning frequency for a given port length, or the port length required for a target tuning frequency, using the 0.732·diameter end correction. Core endpoints use SI units; the speed of sound defaults to 343 m/s. Everything is computed locally and deterministically, so it is instant and private. Ideal for audio, loudspeaker-design, musical-instrument, muffler and acoustic-treatment app developers, bass-reflex and resonator tools, and acoustics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is Helmholtz resonance; for room reverberation use a reverberation API and for standing waves on strings and in pipes a standing-wave API.
api.oanor.com/helmholtz-api
Sound Level API
Acoustics and decibel maths as an API. The decibel endpoint converts between a linear ratio and decibels, in either the power convention (10·log₁₀) or the amplitude/pressure convention (20·log₁₀), in both directions. The combine endpoint adds sound levels the way real (incoherent) sources combine — by energy summation, so two equal 80 dB sources give 83 dB, not 160 — and can also subtract a known source from a measured total. The distance endpoint applies the inverse-square law to a point source in a free field (−6 dB per doubling of distance) to find the level at a new distance. The wavelength endpoint converts between frequency and wavelength for sound, deriving the speed of sound from the air temperature (or a value you provide). Everything is computed locally and deterministically, so it is instant and private. Ideal for audio engineering and live sound, room and architectural acoustics, noise assessment and environmental monitoring, and physics teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. This is acoustics maths; for electrical circuits use an Ohm's-law API and for general unit conversion use a unit API.
api.oanor.com/soundlevel-api
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Read SoundCloud in real time — no login or key needed. Full-text search across everything or specifically tracks, users and playlists; resolve any soundcloud.com URL to its object; and fetch a track's detail and comments, a user's profile, their tracks, playlists, likes, followers and following, a playlist's detail, and the trending charts by genre. Tracks, users and playlists are addressed by numeric id (from search/resolve). The public web client_id is resolved automatically and refreshed on expiry; every call is live (no cache) and returns the upstream SoundCloud shape, paginated with limit + offset. 16 endpoints. Built for music discovery, artist and audience analytics and audio content aggregation. A SoundCloud (creator audio) data API — distinct from the Music API (Deezer commercial catalog). No upstream key, no cache.
api.oanor.com/soundcloud-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Tempo & BPM API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Tempo & BPM API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Tempo & BPM API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Tempo & BPM API cost?
Tempo & BPM API has a free tier with 100 calls / month. Paid plans start at €9.25 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Tempo & BPM API GDPR-compliant?
All requests to Tempo & BPM API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/tempo-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/tempo-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/tempo-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);import requests
r = requests.get(
"https://api.oanor.com/tempo-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
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