Date Info API

REAL DATA

Real calendar facts for any date — weekday, ISO week, day of year, quarter, leap year, days in month, weekend flag and Unix timestamp. Defaults to today.

Authoritative reference data or standards computation

Base URL: /api/date-info
Category: Date & Time
Capabilities: 1 route
Last updated: July 30, 2026

Data source: ISO 8601 calendar arithmetic (proleptic Gregorian)

GET /api/date-info Calendar facts for a date (default: today, UTC) Computed answer

Pure calendar arithmetic — only a bare call (no date) reads the clock, so responses for an explicit date are fully deterministic. The resolved date is echoed in meta.params.date.

Route reference

Code, request parameters, response fields and verified examples 5 params · 10 fields · 3 examples

Code samples Ready-to-copy requests in 4 languages

curl JavaScript Python PHP

curl "https://randomapi.dev/api/date-info"

const res = await fetch("https://randomapi.dev/api/date-info");
const { data, meta } = await res.json();

import requests

data = requests.get("https://randomapi.dev/api/date-info").json()["data"]

$json = json_decode(file_get_contents(
  "https://randomapi.dev/api/date-info"
), true);
$data = $json["data"];

Parameters Route-specific request inputs 1

Parameter	Type	Default & allowed	Description
`date`	date	example: 2026-06-11	Date to analyze: YYYY-MM-DD, or an ISO 8601 timestamp (truncated to its UTC calendar date). Years 1583–9999. Defaults to today (UTC).

date date

Date to analyze: YYYY-MM-DD, or an ISO 8601 timestamp (truncated to its UTC calendar date). Years 1583–9999. Defaults to today (UTC).

example: date=2026-06-11

Universal parameters Shared response and formatting options 4

Parameter	Type	Default & allowed	Description
`fields`	list	example: date,weekday	Return only these fields (comma-separated). Mutually exclusive with 'exclude'.
`exclude`	list	example: unix	Return all fields except these (comma-separated).
`pretty`	boolean	default: false example: true	Pretty-print the JSON response.
`unwrap`	boolean	default: false example: true	Drop the envelope: return the raw array/object without data/meta wrapper.

fields list

Return only these fields (comma-separated). Mutually exclusive with 'exclude'.

example: fields=date,weekday

exclude list

Return all fields except these (comma-separated).

example: exclude=unix

pretty boolean

Pretty-print the JSON response.

default: false

example: pretty=true

unwrap boolean

Drop the envelope: return the raw array/object without data/meta wrapper.

default: false

example: unwrap=true

Response schema Fields returned in each record 10

Field	Type	Description	Example
`date`	string (YYYY-MM-DD)	The resolved UTC calendar date the facts describe.	2026-06-11
`weekday`	string	English weekday name, Monday–Sunday.	Thursday
`isoWeek`	integer	ISO 8601 week number (1–53). Weeks start Monday; week 1 is the week containing the year's first Thursday.	24
`isoWeekYear`	integer	ISO week-based year the week belongs to — differs from the calendar year around New Year (2021-01-01 → 2020).	2026
`dayOfYear`	integer	Ordinal day of the year: 1 (Jan 1) up to 365, or 366 in leap years.	162
`quarter`	integer	Calendar quarter, 1–4 (Q2 = April–June).	2
`isLeapYear`	boolean	Full Gregorian leap rule: divisible by 4, except centuries not divisible by 400 (2000 yes, 1900 no).	false
`daysInMonth`	integer	Length of the date's month in days (28–31).	30
`isWeekend`	boolean	True when the weekday is Saturday or Sunday.	false
`unix`	integer	Unix timestamp in seconds of the date at midnight UTC.	1781136000

date string (YYYY-MM-DD)

The resolved UTC calendar date the facts describe.

example: 2026-06-11

weekday string

English weekday name, Monday–Sunday.

example: Thursday

isoWeek integer

ISO 8601 week number (1–53). Weeks start Monday; week 1 is the week containing the year's first Thursday.

example: 24

isoWeekYear integer

ISO week-based year the week belongs to — differs from the calendar year around New Year (2021-01-01 → 2020).

example: 2026

dayOfYear integer

Ordinal day of the year: 1 (Jan 1) up to 365, or 366 in leap years.

example: 162

quarter integer

Calendar quarter, 1–4 (Q2 = April–June).

example: 2

isLeapYear boolean

Full Gregorian leap rule: divisible by 4, except centuries not divisible by 400 (2000 yes, 1900 no).

example: false

daysInMonth integer

Length of the date's month in days (28–31).

example: 30

isWeekend boolean

True when the weekday is Saturday or Sunday.

example: false

unix integer

Unix timestamp in seconds of the date at midnight UTC.

example: 1781136000

Documented examples

Build-generated requests and complete responses 3

Everything about today /api/date-info

GET /api/date-info

{
  "data": {
    "date": "2026-07-30",
    "weekday": "Thursday",
    "isoWeek": 31,
    "isoWeekYear": 2026,
    "dayOfYear": 211,
    "quarter": 3,
    "isLeapYear": false,
    "daysInMonth": 31,
    "isWeekend": false,
    "unix": 1785369600
  },
  "meta": {
    "endpoint": "date-info",
    "params": {
      "date": "2026-07-30"
    },
    "generatedAt": "2026-07-30T15:14:08.000Z"
  }
}

Facts for a specific date /api/date-info?date=2026-06-11

GET /api/date-info?date=2026-06-11

{
  "data": {
    "date": "2026-06-11",
    "weekday": "Thursday",
    "isoWeek": 24,
    "isoWeekYear": 2026,
    "dayOfYear": 162,
    "quarter": 2,
    "isLeapYear": false,
    "daysInMonth": 30,
    "isWeekend": false,
    "unix": 1781136000
  },
  "meta": {
    "endpoint": "date-info",
    "params": {
      "date": "2026-06-11"
    },
    "generatedAt": "2026-07-30T15:14:08.000Z"
  }
}

Leap-year and month-length check /api/date-info?date=2024-02-29&fields=date,isLeapYear,daysInMonth

GET /api/date-info?date=2024-02-29&fields=date,isLeapYear,daysInMonth

{
  "data": {
    "date": "2024-02-29",
    "isLeapYear": true,
    "daysInMonth": 29
  },
  "meta": {
    "endpoint": "date-info",
    "params": {
      "date": "2024-02-29"
    },
    "generatedAt": "2026-07-30T15:14:08.000Z"
  }
}

About this API

Coverage, behavior and common use cases

Coverage & behavior

Every field is pure Gregorian calendar arithmetic — real, deterministic facts with no datasets and no timezone guessing. Pass a date, or nothing to get today (UTC):

weekday plus isWeekend (true on Saturday and Sunday).
isoWeek / isoWeekYear per ISO 8601: weeks start on Monday and week 1 is the week containing the year's first Thursday. The week-year is not always the calendar year — 2021-01-01 falls in week 53 of 2020, while 2024-12-30 already belongs to week 1 of 2025.
dayOfYear (1–366), quarter (1–4) and daysInMonth (28–31).
isLeapYear using the full Gregorian rule — 2000 was a leap year, 1900 was not.
unix — seconds since the epoch at the date's midnight UTC.

Dates are treated as UTC calendar dates: an ISO timestamp input is truncated to its UTC date (with a warning so you notice), impossible dates like 2026-02-31 are rejected with a 400, and years outside 1583–9999 are refused — the Gregorian calendar simply didn't exist before October 1582, and pretending otherwise would return wrong data.

Use it for

Show ISO week numbers in planners, timesheets and sprint boards
Validate date input server-side: leap years, month lengths, impossible dates
Bucket analytics by quarter, ISO week or day of year without a date library
Disable weekends in delivery and booking date pickers

Frequently asked questions

Practical answers about this endpoint 3

What does it tell me about a date?

Weekday, ISO week and week-year, day of year, quarter, leap-year flag, days in the month, weekend flag and the Unix timestamp — all the calendar facts in one call.

Which date is used if I omit the parameter?

Today — so the bare route answers "what day is it today?" with the live date.

Why does the ISO week-year sometimes differ from the calendar year?

Around New Year, ISO 8601 assigns days to their week's year — January 1 can belong to week 52/53 of the previous ISO year. The API reports both so you don't have to compute it.

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