API · /relativity-api

Special Relativity API

healthy 4,281 Subscribers

Special-relativity maths as an API, computed locally and deterministically. The lorentz endpoint computes the Lorentz factor γ = 1/√(1 − β²) from a velocity (in m/s, km/s or as a fraction of the speed of light β), and — given a proper time or a proper length — the dilated time Δt = γ·Δt₀ that a stationary observer measures and the contracted length L = L₀/γ. The energy endpoint computes the rest energy E₀ = mc², the total energy E = γmc², the kinetic energy KE = (γ − 1)mc² and the relativistic momentum p = γmv of a mass moving at a given speed, reporting the energies in both joules and electronvolts. The mass-energy endpoint applies Einstein's E = mc² to convert between mass and energy in either direction, in joules, electronvolts, megaelectronvolts and kilowatt-hours. The speed of light is exactly 299,792,458 m/s. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics-education, simulation, astronomy and science-communication app developers, relativity and particle-physics tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is special relativity; for everyday SUVAT motion use a kinematics API and for orbital mechanics an orbital API.

#relativity #physics #lorentz #einstein #mass-energy #developer-tools

api.oanor.com/relativity-api

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

/api/relativity-api/openapi.json

/api/relativity-api/llms.txt

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

API health

healthy

Uptime: 100.00%; Server probes · 24h
Avg latency: 87 ms; Server probes · 24h
Subscribers: 4,281; active
Total calls: 28; last 7 days

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Pricing

Pick a tier — billed monthly, cancel anytime.

Free

2,000 calls / month
2 requests / second
Hard cap (429 above quota, no overage)
Lorentz factor gamma from velocity (beta input)
Deterministic, instant local compute
2000 calls/month to evaluate

Starter

€5.00 /month

20,000 calls / month
5 requests / second
Hard cap (429 above quota, no overage)
Lorentz factor + time-dilation maths
20k calls/month for coursework & demos
JSON responses with full precision
Email support

Pro

€15.00 /month

150,000 calls / month
15 requests / second
Hard cap (429 above quota, no overage)
All special-relativity endpoints
150k calls/month for classroom apps
Length-contraction & relativistic energy
Higher 15 rps throughput

Mega

€49.00 /month

1,000,000 calls / month
40 requests / second
Hard cap (429 above quota, no overage)
1M calls/month for high-traffic ed-tech
Mass-energy & momentum endpoints
40 rps burst capacity
Priority support & SLA

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Center of Mass API

Centre-of-mass and barycentre mechanics as an API, computed locally and deterministically. The point-masses endpoint computes the centre of mass of a system of point masses in one, two or three dimensions, applying x_com = Σ(m_i·x_i)/Σm_i to each axis from a list of masses and their x (and optional y and z) coordinates — masses of 1, 2 and 3 at positions 0, 1 and 2 give a centre of mass at 1.333, and four equal masses at the corners of a square sit at its centre. The two-body endpoint computes the barycentre of two masses separated by a distance, r1 = d·m2/(m1+m2) from the first body, which always lies closer to the heavier one — for the Earth-Moon system the barycentre is about 4 670 km from Earth’s centre, still inside the planet. Lists may be passed as comma-separated values (masses=1,2,3&x=0,1,2) or as JSON arrays in a POST body, and units are consistent and unit-agnostic. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics, engineering-statics, astronomy, robotics, game-physics and mechanics-education app developers, balance-point and barycentre tools, and simulation software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 2 endpoints. This is the centre of mass; for the rotational moment of inertia use a moment-of-inertia API.

api.oanor.com/centerofmass-api

Vehicle Braking API

Vehicle-braking physics as an API, computed locally and deterministically. The stopping-distance endpoint computes the total distance to stop a vehicle as the sum of the reaction distance the vehicle travels during the driver's reaction time, v·t, and the braking distance v²/(2·μ·g) — which grows with the square of speed, so doubling the speed quadruples the braking distance — from the speed, the tyre-road friction coefficient, the reaction time and the road grade, along with the deceleration and the time to stop. The braking-force endpoint computes the braking force F = m·a and the deceleration of a vehicle, either from a stop-in-a-given-distance (a = v²/2d) or from the friction coefficient (a = μ·g), with the kinetic energy that must be dissipated as heat. The skid-speed endpoint reconstructs the speed at the start of a skid from the skid-mark length, v = √(2·μ·g·d), a lower-bound estimate used in accident reconstruction. Speed is in km/h by default (also m/s or mph), mass in kg and distances in m; dry asphalt has μ ≈ 0.7, wet ≈ 0.4 and ice ≈ 0.1. Everything is computed locally and deterministically, so it is instant and private. Ideal for automotive, driving-safety, fleet, telematics and accident-reconstruction app developers, stopping-distance and forensic tools, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is vehicle braking; for general kinematics use a kinematics API and for an object on a slope an inclined-plane API.

api.oanor.com/brake-api

Circular Motion API

Uniform circular-motion physics as an API, computed locally and deterministically. The centripetal-force endpoint computes the centripetal acceleration a = v²/r = ω²·r — always pointing toward the centre — and the centripetal force F = m·a that holds a body on its circular path, from the mass, the radius and either the linear or the angular velocity, and reports the equivalent g-force. The angular endpoint converts between every way of describing rotation — angular velocity (rad/s), revolutions per minute, frequency, period and, given a radius, the linear (tangential) velocity — using ω = 2π·f = 2π/T = v/r. The centrifuge endpoint computes the relative centrifugal force (RCF, in g) of a centrifuge rotor from its speed in rpm and radius, RCF = ω²·r / g, or inverts it to give the rpm needed to reach a target RCF. Masses are in kg, radii in m (mm for the centrifuge), velocities in m/s, angular velocities in rad/s and forces in N. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics-education, mechanical, automotive, lab-centrifuge and amusement-ride app developers, rotational-motion and g-force tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is uniform circular motion; for gravitational orbits use a gravitation API, for a vehicle on a banked curve a banked-curve API and for pendulum oscillation a pendulum API.

api.oanor.com/centripetal-api

Nuclear Physics API

Nuclear-physics maths as an API, computed locally and deterministically. The binding-energy endpoint computes a nucleus's mass defect, Δm = Z·m_H + N·m_n − M_atom, and its binding energy E = Δm·c² (1 u = 931.494 MeV) and binding energy per nucleon, from the proton and neutron counts and the measured atomic mass. The semf endpoint estimates the binding energy from the semi-empirical (Bethe-Weizsäcker) mass formula, breaking it into the volume, surface, Coulomb, asymmetry and pairing terms, from just the mass number and proton number. The q-value endpoint computes the energy released or absorbed in a nuclear reaction from the masses of the reactants and products, Q = (Σm_reactants − Σm_products)·c², classifying it as exothermic (fusion of light nuclei or fission of heavy ones) or endothermic. Masses are in atomic mass units and energies in MeV and joules. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics-education, nuclear-engineering, astrophysics and science app developers, reactor and reaction tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is nuclear binding and reactions; for radioactive decay use a half-life API and for atomic energy levels a quantum API.

api.oanor.com/nuclear-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Special Relativity API?

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

What's the rate limit for Special Relativity 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 Special Relativity API cost?

Special Relativity 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 Special Relativity API GDPR-compliant?

All requests to Special Relativity 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.

Relativity 3

Meta 1

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

GET /v1/energy

Relativistic energy

Playground

Parameters

Custom headers

Language: Client:

GET /v1/lorentz

Lorentz factor

Playground

Parameters

Custom headers

Language: Client:

GET /v1/mass-energy

E = mc²

Playground

Parameters

Custom headers

Language: Client:

GET /v1/meta

Spec

Playground

Custom headers

Language: Client:

Code snippets

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

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

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

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Special Relativity API

API health

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Related APIs

Center of Mass API

Vehicle Braking API

Circular Motion API

Nuclear Physics API

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