Countdown to recurring events API

Compute the next occurrence of a recurring event (next Friday-the-13th, next leap day, next New Year, next named weekday) or an explicit target date, plus the exact time-until broken into days/hours/minutes. The recurrence-finding math (e.g. the next Feb 29 or the next Friday the 13th) is something LLMs get wrong; this is deterministic. Answers 'when is the next Friday the 13th', 'how long until the next leap day', 'countdown to New Year', 'time until next Monday'.

Price$0.01per request

MethodPOST

Route/v1/data/countdown

StatusLive

MIME typeapplication/json

Rate limit60/minute

CacheNo cache

datacountdowntime-untilrecurringfriday-13thleap-daynext-occurrencedays-until

API URLhttps://x402.hexl.dev/v1/data/countdown

Integration docs

Example request

{
  "event": "friday-13",
  "from": "2026-06-03T00:00:00Z"
}

Example response

{
  "event": "friday-13",
  "label": "next Friday the 13th",
  "from": "2026-06-03T00:00:00.000Z",
  "next": "2026-11-13T00:00:00.000Z",
  "timeUntil": {
    "totalDays": 163,
    "totalHours": 3912,
    "days": 163,
    "hours": 0,
    "minutes": 0,
    "seconds": 0,
    "human": "163d 0h 0m"
  }
}

Input schema

{
  "type": "object",
  "required": [
    "event"
  ],
  "properties": {
    "event": {
      "type": "string",
      "examples": [
        "friday-13",
        "leap-day",
        "new-year",
        "next-monday",
        "date"
      ]
    },
    "from": {
      "type": "string",
      "examples": [
        "2026-06-03T00:00:00Z"
      ]
    },
    "target": {
      "type": "string",
      "examples": [
        "2026-12-25"
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}