Calendar APIs

Calendarific is a REST API that returns public holidays for over 230 countries and territories, supporting both Gregorian and non-Gregorian calendars.

Checkiday is a holiday data API covering more than 5,000 national days and observances in the United States, including unofficial holidays like National Pizza Day.

Church Calendar (calapi.inadiutorium.cz) is a free, no-auth REST API that returns the Roman Catholic liturgical calendar for any date or month.

The Czech Namedays Calendar API lets you look up the Czech or Slovak nameday (svátek) associated with a given first name, or find whose nameday falls on a specific date.

Festivo is a public holidays API covering more than 60 countries with regional subdivision support, providing both national and state/province-level holidays.

The Google Calendar API allows you to programmatically read, create, update, and delete events on any Google Calendar accessible to the authenticated user.

The Hebcal API provides free Jewish calendar data including Hebrew date conversions, Shabbat candle-lighting times, Jewish holidays, and weekly Torah portion readings.

Holiday API (holidayapi.com) provides historical and current public holiday data for over 100 countries, dating back to 2015.

LectServe is a free REST API that returns Revised Common Lectionary readings — Scripture passages assigned to each Sunday and feast day used by many Protestant denominations.

Nager.Date is a completely free, open-source REST API providing public holidays for over 90 countries with no API key required.

Namedays Calendar provides name day traditions for dozens of countries, letting you look up which names are celebrated on any given date.

Non-Working Days provides ICS calendar files for public holidays and non-working days across many countries, hosted as a structured database on GitHub.

IsDayOff.ru is a minimalist REST API that returns whether a given date is a working day, non-working day, or short (pre-holiday) day for Russia and several CIS countries, as well as the United States.

Abstract's Public Holidays API delivers structured data about national, regional, and religious holidays for countries worldwide.

Russian Calendar API checks whether a specific date is a holiday, working day, or short day in Russia, based on official government decree data.

The UK Bank Holidays API is an official UK government endpoint that returns all bank holidays for England and Wales, Scotland, and Northern Ireland as structured JSON.