Spec

Code snippets

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

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

$ch = curl_init("https://api.oanor.com/rrule-api/v1/meta");
curl_setopt($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/rrule-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": "Recurrence Rule API",
        "notes": "Dates are handled in UTC. An infinite rule (no COUNT or UNTIL) is capped by the count parameter. This expands the recurrence rule; to build a full .ics calendar event use an iCalendar API and for plain date arithmetic use a date-time API. Nothing is stored.",
        "version": "v1",
        "endpoints": [
            {
                "path": "/v1/expand",
                "params": {
                    "count": "max occurrences to return (default 10, max 1000)",
                    "rrule": "the RRULE, e.g. FREQ=WEEKLY;BYDAY=MO,WE,FR;COUNT=10 (required)",
                    "start": "the start date-time, ISO 8601 UTC (required)"
                },
                "returns": "the list of occurrence date-times"
            },
            {
                "path": "/v1/describe",
                "params": {
                    "rrule": "the RRULE (required)"
                },
                "returns": "a plain-English description of the rule"
            },
            {
                "path": "/v1/meta",
                "params": [],
                "returns": "this document"
            }
        ],
        "description": "Expand and describe RFC 5545 recurrence rules (the RRULE behind calendar repeats). The expand endpoint takes an RRULE and a start date-time and returns the next occurrence dates — handling FREQ (daily, weekly, monthly, yearly and finer), INTERVAL, COUNT, UNTIL, BYDAY (including ordinals like 2MO or -1FR for 'last Friday'), BYMONTHDAY (including negatives for 'last day'), BYMONTH and WKST. The describe endpoint turns a rule into a plain-English sentence. Everything is computed locally in UTC and deterministically, so it is instant and private. Pure local, no key."
    },
    "meta": {
        "timestamp": "2026-06-03T09:24:59.199Z",
        "request_id": "f532404e-261f-4210-a09d-d8d050877e35"
    },
    "status": "ok",
    "message": "Meta",
    "success": true
}