$ISO Week$

ISO Week

Math & Calculations Credits / request: 1

Returns the ISO 8601 week-year, week number and Monday-Sunday range of a date.

GET https://api.apikodu.com/api/v1/math/isoweek

Documentation

Overview

ISO week number.

Authentication

Every request requires the x-api-key header. Credits used and remaining quota are returned in response headers (x-api-credits-used, x-api-remaining-credits, x-rate-limit-*).

Request

GET https://api.apikodu.com/api/v1/math/isoweek?date=2026-08-22

Query. Empty uses today UTC.

Parameters

Name	Type	Required	Default	Options	Description
`date`	string	Optional	—	—	YYYY-MM-DD. Empty = today.

Response

Name	Type	Description
`year`	integer	ISO-8601 year. 1 January in week 53 may belong to the previous year.
`week`	integer	ISO week number 1–53. Weeks start on Monday.
`weekday`	integer	ISO weekday. 1=Monday ... 7=Sunday.
`fromDate`	string	Monday of this ISO week YYYY-MM-DD.
`toDate`	string	Sunday of this ISO week YYYY-MM-DD.
`date`	string	Queried date (or today) YYYY-MM-DD.

Errors

HTTP	code	Description
`400`	`-247`	date was sent but is not YYYY-MM-DD.
`401`	`-100`	x-api-key is missing, empty, malformed, inactive, banned, expired, IP-restricted, or not allowed for this API.
`429`	`-221`	Per-minute request limit exceeded. Response headers: x-rate-limit-limit, x-rate-limit-remaining, x-rate-limit-reset.
`429`	—	Package credit quota cannot cover this request. Body may be { error, limit, currentUsage, requestCost } (no code field).
`500`	`-1`	Unexpected server error. message is a generic error text without technical details.

Notes

Success body is { data: { ... } }. Error body is { code, message }. code is an ApiResponseCode enum value (negative integer).

Sample response

{
  "data": {
    "year": 2026,
    "week": 34,
    "weekday": 6,
    "fromDate": "2026-08-17",
    "toDate": "2026-08-23",
    "date": "2026-08-22"
  }
}

Code samples

  
      const response = await fetch('https://api.apikodu.com/api/v1/math/isoweek', {
        method: 'GET',
        headers: {
          'x-api-key': 'YOUR_API_KEY'
        }
      });

      const data = await response.json();
      console.log(data);

  
      import requests

      headers = {
          'x-api-key': 'YOUR_API_KEY'
      }

      response = requests.get('https://api.apikodu.com/api/v1/math/isoweek', headers=headers)
      print(response.json())

  
      using var client = new HttpClient();
      client.DefaultRequestHeaders.Add("x-api-key", "YOUR_API_KEY");

      var response = await client.GetStringAsync("https://api.apikodu.com/api/v1/math/isoweek");
      Console.WriteLine(response);

  
      $response = file_get_contents('https://api.apikodu.com/api/v1/math/isoweek', false, stream_context_create([
          'http' => [
              'header' => "x-api-key: YOUR_API_KEY"
          ]
      ]));

      print_r(json_decode($response, true));

  
      curl -X GET 'https://api.apikodu.com/api/v1/math/isoweek' \
        -H 'x-api-key: YOUR_API_KEY'

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