Date & Time Toolkit

Endpoints (13 live)

• POST /v1/to-jdn — Convert a proleptic-Gregorian calendar date to its Julian Day Number (the integer count of days since JDN 0, 1 January 4713 BC in the proleptic Julian calendar). (0.004 USDC on Base)
• POST /v1/from-jdn — Convert a Julian Day Number back to a proleptic-Gregorian date, with the ISO weekday (1=Monday..7=Sunday) and its name. (0.004 USDC on Base)
• POST /v1/iso-week — Return the ISO-8601 week-numbering year, week number (1..53) and weekday (1=Monday..7=Sunday) for a Gregorian date. The ISO year can differ from the calendar year around New Year. (0.004 USDC on Base)
• POST /v1/easter — Compute the date of Western (Gregorian) Easter Sunday for a year in 1583..9999 using the Anonymous Gregorian computus. (0.004 USDC on Base)
• POST /v1/convert — Convert an ISO datetime into another timezone, with offset, weekday and Unix time. (0.002 USDC on Base)
• POST /v1/between — Compute the calendar breakdown (years, months, days, hours, minutes, seconds) between two ISO 8601 dates/date-times, plus exact totalSeconds. If end precedes start the result is flagged negative rather than erroring. (0.002 USDC on Base)
• POST /v1/parse — Parse an ISO 8601 duration such as 'P1Y2M10DT2H30M' into its components. Returns a normalized ISO string and totalSeconds — but totalSeconds is null when the duration contains years or months, because those are calendar-variable (use /v1/add or /v1/between for exact date math). (0.002 USDC on Base)
• POST /v1/add — Add an ISO 8601 duration to a start date or date-time and return the resulting UTC instant. Calendar-aware: months and years honor month lengths (e.g. Jan 31 + P1M clamps to the last day of February). A negative-signed duration subtracts. (0.002 USDC on Base)
• POST /v1/humanize — Render an ISO 8601 duration as an English phrase, e.g. 'P1Y2M' → '1 year and 2 months'. Components are shown in descending order with correct pluralization. (0.002 USDC on Base)
• POST /v1/weekday — Return the ISO weekday (1=Monday..7=Sunday) and its name for a Gregorian date. (0.004 USDC on Base)
• POST /v1/format — Assemble an ISO 8601 duration string from individual components (years, months, weeks, days, hours, minutes, seconds) and an optional sign. All components must be non-negative and at least one must be non-zero. (0.002 USDC on Base)
• POST /v1/business-days — Add/subtract business days to a date, or count business days between two dates — skipping weekends and optional holidays. (0.002 USDC on Base)
• POST /v1/day-of-year — Return the ordinal day of the year (1..366), the number of days in that year and whether it is a leap year. (0.004 USDC on Base)