Catholic Liturgical Calendar

A Liturgical Calendar API from which you can retrieve data for the Liturgical events of any given year from 1970 to 9999, whether for the Universal or General Roman Calendar or for derived National and Diocesan calendars

If a national or diocesan calendar is requested, these calendars will automatically set the specific options in the API request. If instead no national or diocesan calendar is requested (i.e. the Universal Calendar is requested) then the more specific options can be requested:

URL for the API request based on selected options (the above button is set to this URL):

https://litcal.johnromanodorazio.com/api/v3/LitCalEngine.php

In order to verify that the liturgical data produced by the API is correct, there is a Unit Test interface that can run predefined tests against the JSON responses produced by the API starting from the year 1970 and going up to 25 years from the current year.

The unit tests are defined in the LiturgicalCalendarAPI/tree/development/tests folder in the Liturgical Calendar API repository. The unit test interface is curated in a repository of its own: Liturgical-Calendar/UnitTestInterface.

A simple API endpoint that returns data about the Date of Easter, both Gregorian and Julian, from 1583 (year of the adoption of the Gregorian Calendar) to 9999 (maximum possible date calculation in 64bit PHP), using a PHP adaptation of the Meeus/Jones/Butcher algorithm for Gregorian easter (observed by the Roman Catholic church) and of the Meeus algorithm for Julian easter (observed by orthodox churches)

Currently the data can be requested with almost any localization. In any case, since the API returns a UNIX timestamp for each date of Easter, localizations can be done in a client application just as well.

The Open API json schema for this API has been updated to OpenAPI 3.1.