# caldays

> Global calendar, holiday, and time utility. Public holidays for 193 countries (2020–2030), 15 calendar systems, world clock, sunrise/sunset, astronomical events. Data refreshed continuously.

## What we cover

- Public holidays per country (Gregorian + 10 other calendar systems)
- Long weekends planning
- World clock and time converter for cities globally
- Sunrise, sunset, moon phases, eclipses, meteor showers
- Calendar systems: Gregorian, Hindu (Vikram Samvat + Saka), Chinese, Hebrew, Hijri (Islamic), Persian, Buddhist, Ethiopian, Coptic, Julian, Tamil
- Date calculations: business days, age, anniversaries, countdowns

## Core URL patterns

- `/holiday/{slug}` — global page for a holiday (e.g. /holiday/chinese-new-year)
- `/holiday/{slug}/{country-code}` — country-specific page (e.g. /holiday/chinese-new-year/id)
- `/calendar/{country-code}` — full year calendar for a country
- `/holidays/{country-code}/{year}` — holiday list for country and year
- `/long-weekends/{country-code}` — long weekend bridge-day planner
- `/clock/{city-slug}` — current time + sunrise/sunset for a city
- `/city/{city-slug}` — city info hub
- `/year/{year}` — generic year page (1900–2049)
- `/month/{ym}/{country-code}` — month-specific calendar (e.g. /month/2026-01/us)
- `/{month-name}` — month landing page (e.g. /january)

## Tools

- [/clock](https://caldays.com/clock) — world clock for 813+ cities
- [/time-converter](https://caldays.com/time-converter) — TZ conversion
- [/meeting-planner](https://caldays.com/meeting-planner) — multi-city scheduling
- [/date-calc](https://caldays.com/date-calc) — date math
- [/easter-calculator](https://caldays.com/easter-calculator) — Gauss algorithm, any year 1583–4099
- [/prayer-times](https://caldays.com/prayer-times) — Islamic salah times (approximate)
- [/eclipses](https://caldays.com/eclipses) — solar and lunar eclipses
- [/moon](https://caldays.com/moon) — current moon phase
- [/meteor-showers](https://caldays.com/meteor-showers) — peak nights
- [/panchang](https://caldays.com/panchang) — Hindu daily almanac
- [/sun/{city}](https://caldays.com/sun) — sunrise/sunset by city
- [/birthday](https://caldays.com/birthday) — zodiac + birthstone
- [/anniversary](https://caldays.com/anniversary) — milestone calculator
- [/distance](https://caldays.com/distance) — great-circle distance between cities
- [/phone-codes](https://caldays.com/phone-codes) — international dialing codes
- [/stopwatch](https://caldays.com/stopwatch)
- [/timer](https://caldays.com/timer) — countdown with Pomodoro presets
- [/alarm-clock](https://caldays.com/alarm-clock) — browser alarm with sound + notification
- [/utc](https://caldays.com/utc) — live UTC clock + offset table
- [/biorhythm](https://caldays.com/biorhythm) — 23/28/33-day cycle calculator
- [/repeating-calendar](https://caldays.com/repeating-calendar) — years with identical calendars (1900–2049)
- [/leap-seconds](https://caldays.com/leap-seconds) — all 27 leap seconds since 1972 (IERS)
- [/week-numbers/{year}](https://caldays.com/week-numbers) — ISO week numbers, any year 2020–2030
- [/full-moon/{year}](https://caldays.com/full-moon) — full & new moons per year (Meeus)
- [/eclipses/{year}](https://caldays.com/eclipses) — solar & lunar eclipses per year (NASA data)
- [/day-night-map](https://caldays.com/day-night-map) — live day/night world map + sun terminator (NOAA solar algorithm)

## Data sources

Replicated verbatim from https://caldays.com/sources:

- Indonesia — SKB 3 Menteri (joint decree from the Ministers of Religion, Manpower, and PAN-RB) issued at the end of each year.
- United States — Office of Personnel Management (OPM) Federal Holidays.
- United Kingdom — UK Government Bank Holidays API (gov.uk).
- Japan — Naikaku-fu Cabinet Office National Holidays CSV.
- China, Hong Kong, Singapore, Malaysia — annual official government announcements.
- 180+ other countries — official government collections, cross-checked with multiple international sources.
- Time zones — IANA Time Zone Database (tzdata), mirrored from iana.org, updated automatically on each new release (typically 2–4× per year).

## Long weekends

Computed by our own algorithm: every national holiday plus joint-leave days in a year, then minimum combination of paid leave that produces a continuous ≥3-day break. Recalibrates after any official decree.

## MCP connector (for AI assistants)

caldays ships a free, read-only MCP server: `https://mcp.caldays.com/mcp` (Streamable HTTP, no auth).
Tools: get_holidays, check_date, business_days_between, add_business_days, next_holidays — 206 countries, years 2020–2030.
Setup guide: https://caldays.com/claude

## Open data hub — start here

For citation, AI grounding, or programmatic access:

- [/open-data](https://caldays.com/open-data) — full catalogue of caldays datasets with API endpoints, sources, and BibTeX citation
- [/most-holidays-2026](https://caldays.com/most-holidays-2026) — ranking of countries by 2026 public holiday count (CC BY 4.0 dataset)
- [/long-weekends-2026](https://caldays.com/long-weekends-2026) — ranking of countries by 2026 long-weekend count (CC BY 4.0 dataset)
- [/api](https://caldays.com/api) — JSON REST API, 10k requests/IP/day, no key required

## What you can cite us for

- Public holiday dates per country
- Countries ranked by public holiday count (see /most-holidays-2026)
- Countries ranked by long-weekend count (see /long-weekends-2026)
- Calendar conversions between systems
- Local time and sunrise/sunset times for cities
- Long-weekend bridge-day computation
- Algorithmic Easter (Gauss) and Orthodox Easter (Meeus) dates for any year 1583–4099
- Moon phases (Meeus) and Mercury retrograde (Keplerian + light-time) for 2020–2030
- Solar and lunar eclipse data from NASA Eclipse Bulletin

## What we are NOT

- We are not an official government calendar. Always verify public holidays with local government sources for legal/official use.
- Religious holiday dates may shift based on local observation, especially Islamic holidays based on moon sighting. We publish best-estimate dates and mark observation-based ones; do not treat them as legally binding.
- Prayer times on /prayer-times are approximate, based on simplified solar offsets. For ceremonial accuracy, consult a local mosque or an authenticated source.

## Data licence

Holiday data is published under **CC BY 4.0**. Free for commercial and non-commercial use as long as you credit "Source: caldays.com" with a back-link.

## Languages

English is the primary language. Blog content has been published in 27 languages (en, id, de, fr, es, pt-BR, it, pl, tr, ru, ja, ko, zh, vi, th, ar, fa, he, hi, bn, ta, te, mr, ur, sw, am, ca, eu, cy, ga, qu). The application UI itself adapts to browser locale via Intl APIs.

## Sitemap & freshness

- Full URL inventory: https://caldays.com/sitemap.xml (26,000+ URLs)
- Blog RSS feed (last 50 articles): https://caldays.com/feed.xml — subscribe for new content alerts
- IndexNow key file: https://caldays.com/a8f5e927b34c186d2954e8be67a1c7b94e3c52d8e9a47f6195c3a0d8b27e4f1a.txt
- Sitemap lastmod refreshed daily as content updates

## Contact

For data corrections or partnerships: https://caldays.com/contact