Public holidays for AI assistants

Add the URL below to Claude or another AI assistant, and when asked about holidays or business days it answers from holiday data for 247 countries and regions instead of guessing. The tricky parts are built into the tools: weekends that differ by country (Friday–Saturday in parts of the Middle East), make-up working days such as China’s, and “10 business days from today”. Free, no sign-up.

The URL to add

https://holiday.omikuji.dev/mcp

A remote MCP server (Streamable HTTP, no authentication).

Claude (web and desktop)

In Settings → Connectors, choose “Add custom connector”, then enter a name (for example, World Holidays) and the URL above.

Claude Code

claude mcp add --transport http holiday https://holiday.omikuji.dev/mcp

Other AI assistants

Any assistant that supports remote MCP servers can use the same URL.

Things you can ask

• What date is 10 business days after today for our office in China, counting Chinese New Year and the make-up working days?
• Which days next month are holidays in California?
• Which days in December are business days in both Germany and the UK?
• When are the long weekends in India this year?
• Is next Monday a holiday in Japan?

The assistant gets four tools. Countries are passed as ISO codes (US, CN, DE, …); if omitted, Japan is used.

• check_dates — whether each date is a public holiday, a weekend and a business day
• list_holidays — holidays for a year or a date range
• business_days — the number of business days in a range, or the date N business days later
• find_long_weekends — runs of 3 or more days off

What to expect

• Holidays for 247 countries and regions, from last year to two years ahead. Each holiday is marked official (checked against government data), rule (computed from the legal rules) or estimated (not yet announced, or depends on moon sighting).
• Weekends follow each country, and make-up working days (such as China’s) count as business days. “Today” is the date in the country’s own time zone.
• Days off only for government offices (such as Indonesia’s collective leave) are listed, but counted as days off only with include_government.
• Japan uses the Cabinet Office data from 1955 to 2027, with substitute holidays told apart. Years that have not been announced are not guessed.
• A business day is a day that is neither a weekend nor a public holiday. Company closures (such as Japan’s New Year break) are excluded only when you ask.
• Read-only. No tool writes anything or takes personal information.
• To prevent automated bulk access, each client is limited to 60 requests per minute.