Calendar & date math
ISO weeks, leap years, day-of-year, epoch conversion, and movable-feast dates - the calendar edge cases that are easy to get subtly wrong.
5 tools in this category - 5 free via proof-of-work. ← All tools
ISO week number
FREE w/ compute · or $0.001 ·
POST /api/iso-weekGet the ISO 8601 week number, ISO day-of-week, quarter, and day-of-year for any date. Useful for fiscal/reporting calend…
try in playground →Leap year check
FREE w/ compute · or $0.001 ·
POST /api/leap-yearCheck whether a year is a leap year and get related info: days in that year, the next and previous leap years, and the G…
try in playground →Easter date calculator
FREE w/ compute · or $0.001 ·
POST /api/easter-dateCompute the date of Easter Sunday for a given year using the Anonymous Gregorian algorithm (Meeus/Jones/Butcher). Also r…
try in playground →Epoch / ISO converter
FREE w/ compute · or $0.001 ·
POST /api/epoch-convertConvert between Unix epoch timestamps and ISO 8601 date strings in both directions. Provide either an epoch (seconds or …
try in playground →Day of year
FREE w/ compute · or $0.001 ·
POST /api/day-of-yearGet the day number within the year (1-366) for any date, plus days remaining, leap-year status, percent of year complete…
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