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bizdays

Verified business-day math for AI agents — holidays + per-country weekends, not guesses.

Verified, trustworthy data tools for AI agents. "Qiniso" means "truth" in Zulu.

Website · MCP endpoint · MCP Registry

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LLMs answer "what date is 5 business days after Dec 22nd in the UK?", "how many working days are in this month?", and "is Friday a working day in Saudi Arabia?" confidently and often wrongly — they miscount, forget public holidays, and assume every country's weekend is Saturday/Sunday. bizdays gives an agent the deterministic answer from real public-holiday calendars and per-country weekend rules, showing the weekend rule and the exact holidays it skipped.

Two things break naive business-day math, and bizdays fixes both: weekends aren't Sat/Sun everywhere (Fri/Sat in Saudi Arabia, Egypt & Israel; Fri in Iran; Sun in India; Sat/Sun in the UAE since 2022), and "holiday" must mean a real day off — off-the-shelf data counts observances like Valentine's Day and Christmas Eve, which are not days off.

Counting the working days in a month, a frontier LLM with no tools is wrong 63% of the time, cold — and 23% across business-day questions overall. bizdays: 0%.

Add it to Claude

Settings → Connectors → Add custom connector, and paste — no login, no key:

https://bizdays.qinisolabs.workers.dev/mcp

Stateless, reads no user data, requires no secrets. Prefer to run it locally over stdio? Add { "command": "npx", "args": ["-y", "@qinisolabs/bizdays"] } under mcpServers in your client config.

Use it as a library

Every tool is also a typed function — no MCP required:

npm i @qinisolabs/bizdays

import { addBusinessDays, countBusinessDays, isBusinessDay } from "@qinisolabs/bizdays";

addBusinessDays("2025-12-22", 5, "GB").result;       // "2025-12-31" (skips Christmas + Boxing Day)
countBusinessDays("2025-12-01", "2025-12-31", "US"); // { businessDays: 22, ... }
isBusinessDay("2025-06-13", "SA").isBusinessDay;      // false — Friday is weekend in Saudi Arabia
isBusinessDay("2025-02-14", "US").isBusinessDay;      // true  — Valentine's Day is not a public holiday

Every function returns a rich result: the answer, the weekday, exactly which weekends and named holidays were skipped, the weekend rule and its source, and a confidence flag.

What it does — 6 tools

Tool	What it answers
add_business_days	What date is N working days from a start date? (N may be negative)
count_business_days	How many working days between two dates? (endpoints inclusive by default)
is_business_day	Is this date a working day? If not, why (weekend / public holiday with its name)?
next_business_day	First working day strictly after a date
previous_business_day	Last working day strictly before a date
country_rule	The weekend rule + its source, whether holidays apply, and a confidence flag

Public holidays for 206 countries (and subdivisions) come from date-holidays, filtered to type: "public". Weekends come from Unicode CLDR via the runtime Intl API, plus a curated data/weekend-overrides.json correction layer (e.g. Bangladesh Fri/Sat, Nepal Sat-only) — the maintained data is the moat.

What it is not

• Not all-holidays. It counts weekends and public holidays only — not regional or optional observances. Pass company shutdowns or regional days via extraHolidays.
• Not uniformly verified. A Tier-1 set of ~65 countries is verified; others work but are flagged unverified. Where no holiday calendar exists (e.g. Qatar, Kuwait, Oman), the correct weekend still applies and the response says so (holidaysApplied: false).
• Not a live service dependency. The library makes no network calls; dates are YYYY-MM-DD in UTC.

Architecture

A single TypeScript package exposing one MCP server over two transports — stdio (local / npx) and a Cloudflare Worker (the hosted edge endpoint) — both driven by the same core.ts tool definitions, which also power the importable library.

npm install
npm run build
npm test

License

Apache-2.0. Bundled holiday data is from date-holidays (ISC AND CC-BY-3.0); see NOTICE.