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.

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.

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

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

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

Expands an iCalendar RRULE into occurrence dates between a start and end time.

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

Get precise results every time with our Accurate API for calculating dates and business days—perfect for business professionals.

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.

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.

Calculates business days, SLA due dates, holiday-aware deadlines, skipped weekends and holidays, business hours, and business-time durations.

Schedule weekly events with precision using the Weekly BYDAY Recurrence Weekly BYDAY Recurrence RRULE API.

Utilize the DTSTART-based approach for effective recurrence management with our DTSTART Based Recurrence RRULE API.

Ensure your calendar meets RFC 5545 standards with our compliant RFC 5545 Compliant RRULE API for accurate scheduling.

Streamline your calendar's scheduling process with our Calendar Scheduling Occurrences Calendar Scheduling Occurrences RRULE API.

Simplify recurring event management with our Occurrence Recurring Events Occurrence RRULE API for seamless integration.

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

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

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

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

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

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

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

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

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