{
  "answer": "2028-01-31 is a Monday (ISO week 2028-W05, day 31 of the year). 2028-01-31 plus 1m is Tuesday 2028-02-29 (day clamped to the end of the month).",
  "date": "2028-01-31",
  "weekday": "Monday",
  "iso_week": "2028-W05",
  "day_of_year": 31,
  "leap_year": true,
  "days_in_month": 31,
  "add": {
    "duration": "1m",
    "result": {
      "date": "2028-02-29",
      "weekday": "Tuesday",
      "iso_week": "2028-W09",
      "day_of_year": 60,
      "leap_year": true,
      "days_in_month": 29
    },
    "month_end_clamped": true
  },
  "calendar": "proleptic Gregorian, UTC dates",
  "deterministic": true,
  "docs": "https://bozos.si/tools/fetch#date"
}