MCP connector

Use caldays in Claude — holidays & business days, 206 countries.

caldays ships a free, read-only MCP connector. Once added, Claude can answer holiday and business-day questions for 206 countries (2020–2030) using caldays' open CC BY 4.0 dataset — no account, no API key.

Setup

Add to Claude in 30 seconds

Open Claude (web or desktop) → Settings → Connectors.
Click Add custom connector.
Paste this URL: https://mcp.caldays.com/mcp
Save — no login or API key needed. Ask Claude a holiday question to try it.

5 tools

What Claude can do with it

get_holidays

Get Public Holidays

List the public holidays of any country for any year 2020–2030.

check_date

Check a Specific Date

Weekday, ISO week, weekend status, holiday status and working-day status for one date.

business_days_between

Count Business Days Between Dates

Working days between two dates, excluding weekends and the country's holidays.

add_business_days

Add Business Days to a Date

Deadline math: add 1–365 working days, skipping weekends and holidays.

next_holidays

Get Upcoming Holidays

The next public holidays of a country from any date, with days-from-now counts.

Try it

Example prompts

"What public holidays does Indonesia have in 2026?"

"If I start a 10-business-day review in Germany on 2026-12-18, when does it end?"

"What's the next public holiday in Japan?"

Frequently asked questions

Is it free? Do I need an account?

Yes, free — and no account or API key. The connector serves caldays' open dataset (CC BY 4.0) read-only.

What data does the connector process?

Only the query parameters Claude sends (country code, dates) plus a transient IP address for rate limiting. Nothing is stored. See our privacy policy.

Which countries and years are covered?

206 countries, years 2020–2030 — the window where movable lunar holidays (Eid, Chinese New Year, Diwali era dates) are exact in our dataset.

How are weekends handled?

Weekends are Saturday–Sunday for all countries in v1. Per-country working weeks (e.g. Fri–Sat in some Middle Eastern countries) are not yet in the dataset — tool descriptions state this explicitly.

Claude connector

mcp.caldays.com/mcp