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US federal holidays and business days MCP server

Exact US federal holidays and business-day math, 1971 to 2100.

Connect free Source on GitHub

Free. No key, no sign-in, no paid tier. 5 tools.

Connector URL

https://us-federal-holidays-business-days-mcp.lipmichal.workers.dev/mcp

Paste it as a custom connector in Claude, or add it to Claude Code, Cursor or VS Code. Setup for each is below.

What it knows that a model does not

A model answers from training data. This server reads the source when you ask.

  • Observed-holiday rules: a Saturday holiday moves to Friday, a Sunday holiday to Monday.
  • The Federal Reserve calendar, which stays open on the Friday before a Saturday holiday.
  • Exact date math: add business days, count them, and roll an invoice due date.

Sources OPM federal holiday rules, Federal Reserve holiday schedule, 5 U.S.C. 6103.

Tools (5)

Read from the live server with tools/list on 2026-11-02.

ToolWhat it does
list_federal_holidays List U.S. federal holidays for a year. Exact U.S. federal holidays for any year 1971-2100 under 5 U.S.C. 6103: legal date, OPM observed date (Saturday -> Friday, Sunday -> Monday, so New Year's Day 2022 is observed Friday 2021-12-31) and the Federal Reserve closure date (Fed...
is_business_day Check if a date is a U.S. business day. Says whether a date (1971-2100) is a business day on the U.S. federal (OPM) calendar or the Federal Reserve banking calendar, names the holiday if any, and returns the previous and next business day.
add_business_days Add or subtract U.S. business days. Adds (or with a negative number subtracts) N business days to a date, skipping weekends and observed U.S. federal or Federal Reserve holidays exactly.
count_business_days Count U.S. business days between two dates. Counts business days between two dates (1971-2100) on the U.S. federal or Federal Reserve calendar, excluding weekends and observed holidays. include_start and include_end default to true, like Excel NETWORKDAYS.
invoice_due_date Invoice due date from net terms. Computes an invoice due date from an issue date and net terms in calendar days (Net 30 = 30), then optionally rolls a weekend or U.S. holiday due date: following (next business day), preceding, or modified_following (next business day unless it crosses into the next month).

Connect it

One URL, no token. Pick your app.

Claude.ai and Claude Desktop

Open Settings, then Connectors, then Add custom connector. Paste the URL. Leave the OAuth fields empty. Save.

https://us-federal-holidays-business-days-mcp.lipmichal.workers.dev/mcp

Claude Code

Run this in your terminal. Then run claude mcp list to check it.

claude mcp add --transport http us-federal-holidays-business-days https://us-federal-holidays-business-days-mcp.lipmichal.workers.dev/mcp

Cursor

Merge this into ~/.cursor/mcp.json (all projects) or .cursor/mcp.json (one project).

{
  "mcpServers": {
    "us-federal-holidays-business-days": {
      "url": "https://us-federal-holidays-business-days-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

VS Code

Put this in .vscode/mcp.json. The top key is servers, not mcpServers.

{
  "servers": {
    "us-federal-holidays-business-days": {
      "type": "http",
      "url": "https://us-federal-holidays-business-days-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

Prefer to run it on your machine? It is on npm: npx -y us-federal-holidays-business-days-mcp (needs Node.js).

Things to ask

Paste one into a new chat after you connect.

Sourcegithub.com/theluckystrike/us-federal-holidays-business-days-mcp RelatedCreate an invoice in Claude npmus-federal-holidays-business-days-mcp

Questions

Is the US federal holidays and business days MCP server free?
Yes. The hosted URL is free and needs no token, key or account. The source is open on GitHub.
Why not just ask the model?
A model answers from its training data. That data stops at a cutoff date, and long sums can drift. This server reads its data or rules each time you ask, so the answer is current and exact.
Where does the data come from?
OPM federal holiday rules, Federal Reserve holiday schedule, 5 U.S.C. 6103.
Which apps can use it?
Any MCP client that accepts a remote server URL: Claude.ai and Claude Desktop custom connectors, Claude Code, Cursor, VS Code and others. You can also run it locally with npx.

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