Conception date from a last menstrual period or from a known due date, as ISO 8601 dates

Antenatal visit dates from the WHO 2016, NICE or ACOG published schedules, as calendar dates.

Due date from last menstrual period using Naegele's rule, with 21-45 day cycle length correction.

Dating from BPD, HC, AC and FL measurements in millimetres, using Hadlock 1984 equations.

Convert dates between Gregorian, Hebrew, Islamic and Chinese calendars; holidays by year.

Convert dates between 13 calendars and get Islamic, Jewish, Chinese and Persian holiday dates (Ramadan, Eid, Passover, Chinese New Year, Nowruz) for 1900-2100.

Pregnancy due date and gestational age API. EDD from LMP, conception, IVF transfer day, or ultrasound CRL. ACOG redating rules, trimester, and term milestones. Deterministic ISO 8601 dates.

Gestational age at any given date, returned as a 29w2d label and as total days.

Due date from embryo transfer date. Day-3, day-5, day-6 and egg retrieval calculated separately.

Trimester boundaries, 24w0d viability, and four preterm and four term classes with their dates.

Applies ACOG Committee Opinion 700 Table 1 to decide whether an ultrasound overrides LMP dating.

Ovulation estimate and 6-day fertile window from cycle length. Not contraceptive guidance.

Embark on a temporal journey with the World Time API – your global clock for instant access to the current date and time in any city. Seamlessly integrating with applications, this API synchronizes the world, ensuring users stay connected to the heartbeat of time across diverse corners of the globe.

Accurate business-day, holiday, and scheduling math for major countries and their subdivisions — without maintaining a single holiday calendar yourself. Add or subtract working days, check if a date is a business day, find the next valid date, or count working days between two dates, with full support for regional subdivisions, custom weekends, and your own blackout dates. One simple GET call, instant JSON.

The Global Time API is a valuable resource that makes it easy for developers to access accurate and up-to-date time and date information for countries around the world.

The Global API delivers seamless date and business day calculations worldwide, catering to international business needs.

Ultimate Chinese Calendar API is a tool that provides information related to the Chinese lunar calendar, also known as the Chinese lunisolar calendar. This calendar is used in several countries, including China, Taiwan, and Vietnam, and is based on the movements of the moon.

Count working days between two dates or add business days to a date, skipping weekends and public holidays of 100+ countries and regions.

Calculate business days accurately while accessing global holiday data to optimize your workflows.

Convert any date and time between world time zones with correct daylight saving handling, get the current time of any zone with its offset, or list every supported zone name. Daylight saving rules follow the standard worldwide zone database.

Trust our Reliable API for consistent date and business day calculations, ensuring you never miss a deadline again.

Enhance your scheduling with the Smart API, designed to simplify date and business day calculations with intelligence.

Libera.Date.Api is a high-precision date calculation engine designed to streamline business logic for global applications. Its core strength lies in its advanced Working Days System, which accurately calculates business days by automatically excluding weekends and public holidays for multiple countries (including 100 countries). Beyond simple duration checks, the API offers intelligent scheduling tools like finding the nearest available working day, analyzing date ranges for non-working intervals, and distinguishing between standard weekends and legal holidays. Whether you are computing SLAs, planning delivery windows, or building HR rosters, Libera.Date.Api ensures your dates align with real-world business calendars.

Ensure timely project deliveries with the SLA Deadline Calculator, using global holidays for precise deadline calculations.

Look up public holidays for 55 countries, calculate business day deadlines, find the next business day, export holidays to iCal, and more — all backed by versioned JSON data with no external dependencies at runtime. Covers 55 countries across Africa, Americas, Asia, Europe and Oceania for years 2024 to 2027.