API · /schwarzschild-api

Black Hole Physics API

healthy 4,656 Subscribers

Black-hole general-relativity maths as an API, computed locally and deterministically. The radius endpoint computes the Schwarzschild radius r_s = 2GM/c² — the event horizon of a non-rotating black hole — from a mass given in kilograms or solar masses, together with the photon sphere at 1.5·r_s and the innermost stable circular orbit (ISCO) at 3·r_s; the Sun would have an event horizon about 2.95 km across and the Earth about 9 mm. The time-dilation endpoint computes the gravitational time-dilation factor √(1 − r_s/r) at a distance r from a mass — a clock deep in a gravity well ticks slower than a far-away clock, and at the horizon time appears to stop. The hawking endpoint computes the Hawking temperature T = ħc³/(8πGMk_B), which is higher for smaller black holes, and the evaporation time, which scales as the cube of the mass — a solar-mass black hole would take about 10^67 years to evaporate. Masses are in kilograms or solar masses and distances in metres, using G, c, ħ and the Boltzmann constant. Everything is computed locally and deterministically, so it is instant and private. Ideal for astrophysics, cosmology, science-communication, simulation and education app developers, black-hole and relativity tools, and physics teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is general-relativity black-hole physics; for special relativity (Lorentz factor, E=mc²) use a relativity API.

#black-hole #schwarzschild #general-relativity #hawking #astrophysics #developer-tools

api.oanor.com/schwarzschild-api

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Machine-readable spec so AI agents can integrate this API.

/api/schwarzschild-api/openapi.json

/api/schwarzschild-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy

Uptime: 100.00%; Server probes · 24h
Avg latency: 86 ms; Server probes · 24h
Subscribers: 4,656; active
Total calls: 20; last 7 days

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Pricing

Pick a tier — billed monthly, cancel anytime.

Free

3,750 calls / month
2 requests / second
Hard cap (429 above quota, no overage)
3,750 calls/month
2 req/sec
Radius + time dilation + Hawking
No credit card

Starter

€5.00 /month

35,500 calls / month
6 requests / second
Hard cap (429 above quota, no overage)
35,500 calls/month
6 req/sec
Photon sphere, ISCO, evaporation
Email support

Pro

€14.00 /month

216,500 calls / month
15 requests / second
Hard cap (429 above quota, no overage)
216,500 calls/month
15 req/sec
Cosmology & simulation pipelines
Priority support

Mega

€44.00 /month

1,305,000 calls / month
40 requests / second
Hard cap (429 above quota, no overage)
1,305,000 calls/month
40 req/sec
Platform scale
Dedicated SLA

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Tidal Forces API

Tidal-physics and gravitational-dominance astrophysics as an API, computed locally and deterministically. The tidal-force endpoint computes the tidal (differential) acceleration that stretches a body, a = 2·G·M·r/d³, from the primary mass, the radius (half-size) of the affected body and the centre-to-centre distance — and the force if a body mass is given; tidal effects fall off as the inverse cube of distance, far faster than gravity's inverse square, which is why they matter only close in. The roche-limit endpoint computes the Roche limit, the distance inside which tidal forces tear a satellite apart, for both rigid bodies, d = R·(2·ρM/ρm)^(1/3), and fluid bodies, d = 2.44·R·(ρM/ρm)^(1/3), from the primary radius and the two densities — Saturn's rings sit inside its Roche limit. The hill-sphere endpoint computes the Hill-sphere radius, r_H ≈ a·(1−e)·(m/3M)^(1/3), the region where a body's own gravity dominates so it can keep moons, from the orbital distance, eccentricity and the two masses. Masses are in kilograms, distances and radii in metres and densities in kg/m³, with G = 6.674×10⁻¹¹. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, astrophysics, planetary-science, simulation and education app developers, ring-system and moon-stability tools, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is tidal and gravitational-dominance physics; for Newtonian gravity use a gravitation API and for orbital periods an orbital-mechanics API.

api.oanor.com/tidal-api

Star Magnitude & Distance API

Stellar magnitude and distance maths as an API, computed locally and deterministically. The magnitude endpoint works the distance modulus, m − M = 5·log₁₀(d/pc) − 5 — give any two of the apparent magnitude m, the absolute magnitude M and the distance and it returns the third, with the distance in parsecs, light-years and astronomical units (the absolute magnitude is the apparent magnitude a star would have at 10 parsecs). The flux endpoint applies Pogson's relation to turn a magnitude difference into a brightness ratio, F₁/F₂ = 10^(0.4·(m₂ − m₁)), where five magnitudes is exactly a hundredfold change in brightness — from two magnitudes, a magnitude difference or a ratio. The parallax endpoint converts a parallax angle into a distance, d(pc) = 1 ÷ p(arcseconds), and back, the geometric method behind the parsec itself. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy-education, planetarium, stargazing and science app developers, observing and astrophysics tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is stellar magnitude and distance; for orbital mechanics use an orbital API and for great-circle distances on Earth a geo-distance API.

api.oanor.com/starmagnitude-api

Equine Care API

Horse-care maths as an API, computed locally and deterministically — the everyday numbers a horse owner, barn manager or vet tech runs without reaching for a chart. The weight endpoint estimates body weight from a weight-tape measurement using the classic formula weight ≈ heart girth² × body length ÷ a type divisor (adult 330, yearling 301, weanling 280, pony 299) with measurements in inches — a horse with a 72-inch girth and 66-inch length comes out at about 1,037 lb (470 kg), the number you actually dose wormer and feed against. The feed endpoint turns body weight and a goal into daily forage: horses eat roughly 1.5–2.5 % of body weight in dry-matter forage a day, so a 1,000 lb horse on maintenance wants about 15–20 lb of hay, more to gain and less to slim. The gestation endpoint gives the foaling due date and the normal 320–362 day window from a breeding date — a mare bred on 1 April is due around 7 March the next year, give or take three weeks. Everything is computed locally and deterministically, so it is instant and private. Ideal for barn-management and horse-care apps, breeding and foaling trackers, feed-calculator and tack-shop sites, and equine-vet tools. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. Educational estimates — not veterinary advice.

api.oanor.com/equine-api

Darkroom API

Analog darkroom and film maths as an API, computed locally and deterministically — the three corrections that bite when you develop film and make prints by hand. The reciprocity endpoint corrects long exposures for reciprocity failure, where film loses sensitivity past about a second: corrected time = metered^p (Schwarzschild p ≈ 1.3 for many films, settable per datasheet), so a metered 10-second exposure really wants about 20 seconds, a full stop more, while anything under the threshold is left untouched. The printexposure endpoint adjusts enlarger exposure when you change print size — light spreads as you raise the head, so exposure is proportional to (magnification + 1)², where magnification is print size ÷ negative size: going from 2× to 4× magnification turns a 10-second exposure into 27.8 seconds, about 1.5 stops, ready for f-stop printing. The pushpull endpoint scales development time for pushing or pulling film by N stops — time = base × factor^stops, roughly +40 % per stop pushed — turning a 7-minute base into 13.7 minutes at +2 stops, or 5 minutes pulled a stop. Everything is computed locally and deterministically, so it is instant and private. Ideal for film-photography and darkroom apps, light-meter and timer companions, lab and workshop tools, and analog-photography sites. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. For digital depth-of-field use a photography API; for lab molarity use a dilution API.

api.oanor.com/darkroom-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Black Hole Physics API?

Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Black Hole Physics API with the x-oanor-key header. No credit card needed for the free tier.

What's the rate limit for Black Hole Physics 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 Black Hole Physics API cost?

Black Hole Physics API has a free tier with 100 calls / month. Paid plans start at €5.00 / 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 Black Hole Physics API GDPR-compliant?

All requests to Black Hole Physics 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.

BlackHole 3

Meta 1

Pick an endpoint from the list on the left to see its details and try it.

GET /v1/hawking

Hawking temperature

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Parameters

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GET /v1/radius

Schwarzschild radius

Playground

Parameters

Custom headers

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GET /v1/time-dilation

Gravitational time dilation

Playground

Parameters

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GET /v1/meta

Spec

Playground

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Code snippets

curl https://api.oanor.com/schwarzschild-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."

const res = await fetch("https://api.oanor.com/schwarzschild-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();

$ch = curl_init("https://api.oanor.com/schwarzschild-api/SOME_PATH");
curl_setopt($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/schwarzschild-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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Black Hole Physics API

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Related APIs

Tidal Forces API

Star Magnitude & Distance API

Equine Care API

Darkroom API

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