Age from remaining fraction
API · /halflife-api
Half-Life Decay API
healthy
4,792 Subscribers
Radioactive (exponential) decay maths as an API, computed locally and deterministically. The decay endpoint computes how much of a substance remains after a given time, N(t) = N0·(1/2)^(t/T½) = N0·e^(−λt): from a half-life (or a decay constant or mean lifetime), an elapsed time and an optional initial amount, it returns the fraction and percent remaining, the remaining and decayed amounts, the number of half-lives elapsed, and — if you give an initial activity — the remaining activity, which decays by the same factor. The constant endpoint converts freely between the half-life T½, the decay constant λ = ln2/T½ and the mean lifetime τ = 1/λ = T½/ln2. The age endpoint reverses the decay to find the elapsed time from the fraction remaining, t = T½·log₂(1/fraction) — the basis of radiometric (carbon-14) dating — and accepts either a fraction or a remaining and initial amount. Time and half-life share one unit, and the results come out in that unit. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics and chemistry education, nuclear-medicine and dosimetry tools, archaeology and geology dating, and pharmacokinetics and science apps. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is exponential decay; for the ideal gas law use a gas-law API and for the chemical elements use an elements API.
api.oanor.com/halflife-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 90 ms
- Server probes · 24h
- Subscribers
- 4,792
- active
- Total calls
- 36
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 3,000 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- Remaining-mass decay endpoint
- Single isotope per call
- Deterministic, no rate-limit surprises
Starter
€5.00 /month
- 40,000 calls / month
- 5 requests / second
- Hard cap (429 above quota, no overage)
- Remaining mass + elapsed-time solver
- Half-life <-> decay-constant conversion
- Activity (becquerel) output
- Email support
Pro
€15.00 /month
- 250,000 calls / month
- 15 requests / second
- Hard cap (429 above quota, no overage)
- Multi-step decay-chain support
- Carbon-14 / isotope dating endpoint
- Batch sample evaluation
- Priority response queue
Mega
€49.00 /month
- 1,547,000 calls / month
- 40 requests / second
- Hard cap (429 above quota, no overage)
- Highest throughput for classroom/LMS apps
- Bulk decay-curve generation
- Full isotope library presets
- SLA-backed uptime
Built by
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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 Half-Life Decay API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Half-Life Decay API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Half-Life Decay 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 Half-Life Decay API cost?
Half-Life Decay 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 Half-Life Decay API GDPR-compliant?
All requests to Half-Life Decay 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/halflife-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/halflife-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/halflife-api/SOME_PATH");
curl_setopt($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/halflife-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
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