Liturgical Calendar API
Liturgical Calendar API provides structured access to the Roman Catholic liturgical calendar, returning daily liturgical season, calendar celebration (feast day, solemnity, memorial, or feria), liturgical color, and any special observances for any given date. The API supports the traditional Latin Mass calendar as well as the modern Ordinary Form calendar established by the Second Vatican Council, enabling Catholic parishes, seminaries, religious communities, and Catholic app developers to build liturgically-aware applications that keep track of the Church's annual cycle of feasts and seasons.
The Catholic liturgical year is divided into seasons — Advent, Christmas, Ordinary Time (first section), Lent, Easter (Eastertide), and Ordinary Time (second section) — each with its own character, prayers, and scriptural focus. The Liturgical Calendar API returns which season applies to any date, enabling apps to display liturgically appropriate content, background imagery, color themes, or devotional content that matches the current season. Nigerian Catholic parishes serving large congregations can use this to build parish apps or digital noticeboards that automatically update to show the current season and celebration.
Daily celebration data includes the name of the feast or memorial being observed, its rank (solemnity ranks highest, followed by feast, memorial, optional memorial, and feria for ordinary days), and whether it is an obligatory observance or optional. For Nigerian Catholics who observe not only universal feasts but also feasts of particular importance to the Nigerian Church (such as feasts of African saints), the API's data provides the universal calendar foundation that parish administrators can supplement with local observances.
Liturgical color data returned by the API indicates which color vestments and decorations are prescribed: violet for Advent and Lent, white for Christmas, Easter, feasts of the Lord and of Mary, green for ordinary time, and red for Pentecost and feasts of martyrs. Catholic school app developers in Nigeria can use liturgical color data to update digital displays in school chapels, helping students and staff observe the liturgical season visually.
The API covers multiple years, allowing Catholic app developers to build liturgical calendars that display weeks or months ahead rather than only today's celebration. Parish bulletin generation tools can query the week ahead to automatically include the proper feast names for each Sunday and weekday Mass in weekly bulletins. Nigerian parishes that produce printed or digital Sunday bulletins can automate this liturgical data insertion, reducing manual data entry for parish secretaries.
Religious education platforms and apps for Catholic schools in Nigeria can use the API to contextualize lessons within the liturgical year — teaching students about the significance of current feasts, saints being commemorated, and the theological meaning of each season. The API is free and open for use without registration, making it immediately accessible for Nigerian Catholic ministry app developers working with limited budgets for parish or school projects. The API is hosted at calapi.inadiutorium.cz and returns data in JSON format. No authentication key is required — simply pass the date as a URL path parameter to retrieve the liturgical data for that day. Nigerian Catholic developers can integrate this API into parish management systems to automatically populate weekly Mass schedules with the correct celebration names and liturgical colors, reducing administrative work for parish staff. The free and open nature of the API makes it suitable for volunteer-built parish apps where budget is not available for paid data sources. Future-proofing parish apps with Liturgical Calendar API ensures they remain liturgically accurate across years without requiring manual calendar updates annually.