Spec

Code snippets

curl "https://api.oanor.com/probability-api/v1/meta" \
  -H "x-oanor-key: oanor_test_..."

await fetch("https://api.oanor.com/probability-api/v1/meta", {
  headers: { "x-oanor-key": "oanor_test_..." }
});

$ch = curl_init("https://api.oanor.com/probability-api/v1/meta");
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$out = curl_exec($ch);

import requests
requests.get(
    "https://api.oanor.com/probability-api/v1/meta",
    headers={"x-oanor-key": "oanor_test_..."}
)

Example response

A real response from this endpoint, captured by the latest health check.

{
    "data": {
        "name": "Probability API",
        "notes": "Normal CDF via the erf approximation; inverse via Acklam's algorithm. Combinatorics is exact big-integer. Nothing is stored.",
        "version": "v1",
        "endpoints": [
            {
                "path": "/v1/binomial",
                "params": {
                    "k": "successes",
                    "n": "trials",
                    "p": "success probability 0-1"
                },
                "returns": "PMF, CDF, mean, variance, sd"
            },
            {
                "path": "/v1/poisson",
                "params": {
                    "k": "occurrences",
                    "lambda": "rate"
                },
                "returns": "PMF, CDF, mean, variance, sd"
            },
            {
                "path": "/v1/normal",
                "params": {
                    "x": "a value",
                    "sd": "default 1",
                    "mean": "default 0",
                    "probability": "or a probability to get the quantile"
                },
                "returns": "z-score, PDF, CDF and percentile (or the value for a probability)"
            },
            {
                "path": "/v1/combinatorics",
                "params": {
                    "n": "total",
                    "r": "chosen",
                    "op": "combinations|permutations|factorial"
                },
                "returns": "the exact count"
            },
            {
                "path": "/v1/meta",
                "params": [],
                "returns": "this document"
            }
        ],
        "description": "Probability distributions and combinatorics as an API. The binomial endpoint gives the probability of exactly k successes in n trials (PMF), the cumulative probability up to k (CDF), and the mean, variance and standard deviation. The poisson endpoint does the same for the Poisson distribution from a rate λ. The normal endpoint computes the z-score, probability density, cumulative probability (CDF) and percentile for a value under a normal distribution with any mean and standard deviation — and runs in reverse, turning a probability into the value (the quantile / inverse CDF) and z-score. The combinatorics endpoint computes combinations (nCr), permutations (nPr) and factorials with exact big-integer arithmetic. Everything is computed locally and deterministically, so it is instant and private. Ideal for data science and statistics, quality control and A/B-test planning, gaming and gambling odds, risk modelling, and statistics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. This is probability theory; for descriptive statistics on a dataset use a statistics API and for general expression evaluation use a math API."
    },
    "meta": {
        "timestamp": "2026-06-03T17:42:06.195Z",
        "request_id": "f7248d98-e4ce-4133-94a4-949619da495e"
    },
    "
…