HolidayFYI is a world holidays encyclopedia that helps people explore public holidays, religious observances, and cultural celebrations across more than 250 countries. Its reference content brings together holiday dates, histories, traditions, and country-specific information, making it useful for learning about celebrations and planning around them. Visitors can browse holidays by country, view occasions happening today, and explore upcoming dates through monthly and annual calendars.

The site also features guides, a blog, and a glossary covering holiday customs and calendar systems, alongside comparisons, seasonal information, and notable weeks. Interactive tools and countdowns help users track important dates, while subscription options include calendar downloads in. ics format and holiday feeds.

For developers, HolidayFYI provides an API. The encyclopedia is available in 15 languages, including English, French, Spanish, Chinese, Japanese, Arabic, and Hindi, giving a broad international audience ways to discover and understand occasions such as Diwali, Christmas, Eid, Chuseok, and national days