13 Services from datetime.openverbs.com

Add or subtract business days to a date, or count business days between two dates, skipping weekends and optional custom holidays.

Computes the exact date of Western (Gregorian) Easter Sunday for any year between 1583 and 9999 using the Anonymous Gregorian computus algorithm.

Returns the ISO weekday number (1=Monday through 7=Sunday) and its name for a given Gregorian calendar date.

Converts an ISO 8601 datetime to a target IANA timezone, returning the converted time with UTC offset, weekday, and Unix timestamp.

Returns the ISO 8601 week-numbering year, week number (1–53), and weekday (1=Monday…7=Sunday) for a given Gregorian calendar date.

Computes the calendar breakdown (years, months, days, hours, minutes, seconds) and total seconds between two ISO 8601 dates or date-times, flagging negative results when end precedes start.

Converts an ISO 8601 duration string (e.g. 'P1Y2M10D') into a readable English phrase with correct pluralization and descending component order.

Returns the ordinal day of the year (1–366), total days in that year, and whether the year is a leap year for a given Gregorian date.

Parses an ISO 8601 duration string into its component parts and returns a normalized ISO string plus totalSeconds (null when years or months are present).

Converts a Julian Day Number (JDN) to its proleptic-Gregorian calendar date, ISO weekday number (1=Monday..7=Sunday), and weekday name.

Adds (or subtracts) an ISO 8601 duration to a start date or datetime, returning the resulting UTC instant with calendar-aware handling of month/year boundaries.

Converts a proleptic-Gregorian calendar date (year, month, day) to its Julian Day Number (JDN), the integer count of days since JDN 0.

Assembles a valid ISO 8601 duration string (e.g. P1Y2M10DT2H30M) from individual numeric components (years, months, weeks, days, hours, minutes, seconds) and an optional sign.