Calendar facts for a date (ISO week, quarter, fiscal) API

Return ISO-8601 week number & week-year, quarter, day-of-year, days remaining in the year, weekday, leap-year flag, a configurable fiscal-year/quarter mapping, and a relative description ('3rd Wednesday of the month'). ISO week numbering and fiscal mapping are fiddly and LLMs get them wrong; this is deterministic. Answers 'what ISO week is this date', 'which quarter is this', 'day of year', 'fiscal year for a date with an October fiscal start'.

Price$0.01per request

MethodPOST

Route/v1/data/week-info

StatusLive

MIME typeapplication/json

Rate limit60/minute

CacheNo cache

dataweekiso-weekquarterday-of-yearfiscal-yearcalendarweek-number

API URLhttps://x402.hexl.dev/v1/data/week-info

Integration docs

Example request

{
  "date": "2026-06-03",
  "fiscalYearStartMonth": 10
}

Example response

{
  "date": "2026-06-03",
  "weekday": "Wednesday",
  "isoWeek": 23,
  "isoWeekYear": 2026,
  "isoString": "2026-W23-3",
  "quarter": 2,
  "dayOfYear": 154,
  "daysRemainingInYear": 211,
  "isLeapYear": false,
  "daysInYear": 365,
  "fiscalYearStartMonth": 10,
  "fiscalYear": 2026,
  "fiscalQuarter": 3,
  "relative": "first Wednesday of the month",
  "isLastWeekdayOfMonth": false,
  "isLastDayOfQuarter": false
}

Input schema

{
  "type": "object",
  "required": [
    "date"
  ],
  "properties": {
    "date": {
      "type": "string",
      "examples": [
        "2026-06-03"
      ]
    },
    "fiscalYearStartMonth": {
      "type": "number",
      "examples": [
        10,
        1
      ]
    }
  }
}

Output schema

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