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DATES TOOL

Custom Business Day Checker

Classify dates using an explicit ISO weekday mask and user-supplied holiday list.

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LESS BUSYWORK, MORE DONE

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Business day checker online

Classify dates using an explicit ISO weekday mask and user-supplied holiday list. Use this to inspect or plan dates and time windows from explicit reference values. Fixed examples make the result independent of the date on which this page is opened.

How to use it

Paste the multi-line input in the format shown below. Supply holiday dates yyyy-mm-dd in the second input. Set working iso weekdays. Choose Run tool. Review the output, then copy or download it.

Options and example settings

Option	Choices / value	Example default
Working ISO weekdays	Enter working iso weekdays.	1,2,3,4,5

Worked examples

Use this to inspect or plan dates and time windows from explicit reference values. Fixed examples make the result independent of the date on which this page is opened.

Reproducible worked example

Settings: Working ISO weekdays: 1,2,3,4,5

Input:

2026-10-19
2026-10-20
2026-10-24

Holiday dates YYYY-MM-DD:
2026-10-20

With the input and settings above, the tool produces:

Output:

[
  {
    "date": "2026-10-19",
    "isoWeekday": 1,
    "holiday": false,
    "businessDay": true
  },
  {
    "date": "2026-10-20",
    "isoWeekday": 2,
    "holiday": true,
    "businessDay": false
  },
  {
    "date": "2026-10-24",
    "isoWeekday": 6,
    "holiday": false,
    "businessDay": false
  }
]

The example returns 3 top-level items in an array. Each item is a record; the first record contains “date”, “isoWeekday”, “holiday”, “businessDay”.

Limitations and common mistakes

Uses explicit UTC or offset-bearing inputs and Gregorian dates. No automatic timer, holiday feed or country-specific business rule is applied.
Combined input is bounded to 150,000 characters; output text is bounded to 1.2 million characters. Some algorithms impose smaller limits, stated in their error messages.
Both inputs must follow their own documented format. Changing direction or mode can require different input; the example is for the displayed settings.

Frequently asked questions

What format should I enter?

Paste the multi-line input in the format shown below. The second input is holiday dates yyyy-mm-dd. The worked example shows the supported structure and actual output.

How can I check a custom business calendar day online?

Paste the multi-line input in the format shown below. Supply holiday dates yyyy-mm-dd in the second input. Set working iso weekdays. Choose Run tool. Review the output, then copy or download it.

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.