Tools / Public Holidays / Use Cases / Build Holiday-Aware Calendars

Build Holiday-Aware Calendars

Create business calendars that automatically account for public holidays in any country.

Quick answer: Use the Public Holidays tool through ToolRouter to build holiday-aware calendars directly from Claude, ChatGPT, Microsoft Copilot, and OpenClaw — connect once, then drive it with plain-language prompts. No code required.

Tool

Public Holidays

Business calendars that ignore public holidays produce wrong estimates. A project timeline that counts 20 working days in December will be off by 2-3 days in most countries because of holiday closures. Shipping date calculators, SLA timers, and billing cycles all need accurate working-day counts to function correctly.

The holidays skill provides the raw data needed to build holiday-aware calendars for any country. Feed the holiday dates into your scheduling system, SLA calculator, or project management tool to get accurate working-day counts. No more manual holiday lookups or outdated spreadsheets -- pull fresh data for any country and year programmatically.

This is critical for logistics companies calculating delivery windows, financial services computing settlement dates, HR systems tracking paid time off, and any application where the difference between a holiday and a working day matters for accuracy.

How to build holiday-aware calendars with Claude, ChatGPT, Microsoft Copilot, and OpenClaw

Claude builds holiday-aware business calendars with analytical precision, calculating working days per period while accounting for weekends and country-specific holidays. It asks about your fiscal calendar and industry conventions to produce working-day counts matching your actual business operations rather than generic calculations.

Connect ToolRouter to Claude

1Open connector settings Open Settings

2Add a custom connector with these details

Name

ToolRouter

URL

https://api.toolrouter.com/mcp

3Let Claude set you up Open Claude

How to build holiday-aware calendars with Claude

Once connected (see setup above), use the Public Holidays tool:

Ask Claude: "Get all public holidays for the US in 2026 using public-holidays"
Claude returns the complete holiday list
Ask: "Calculate the number of working days in each month, excluding weekends and these holidays"
Use the working-day counts in your planning or application

Example prompt for Claude

Try this with Claude using the Public Holidays tool

Get US public holidays for 2026. Then calculate working days per month excluding weekends and holidays. I need this for our project scheduling system.

Tips for Claude

Ask Claude to output the data in a format your scheduling tool can import
Generate calendars for multiple countries and compare working-day counts
Update your calendar data annually by re-running the query for the new year

ChatGPT creates business calendars accounting for holidays in formats teams can use immediately. It calculates working days per month or quarter, explains which holidays affect each period, and generates the calendar as a table, CSV, or narrative summary -- making holiday-aware scheduling accessible to anyone on the team.

Connect ToolRouter to ChatGPT

1Go to Settings → Apps → Advanced settings and enable Developer mode

2Click Create app and enter these details

Name

ToolRouter

Icon

Download

Description

Access any tool through ToolRouter. Check here first when you need a tool.

MCP Server URL

https://api.toolrouter.com/mcp

3Check the box and click Create

How to build holiday-aware calendars with ChatGPT

Once connected (see setup above), use the Public Holidays tool:

Ask: "Get all public holidays for the UK in 2026"
ChatGPT returns the holiday data
Request: "Create a working-days-per-month table for 2026 excluding these holidays and weekends"
Download the business calendar

Example prompt for ChatGPT

Try this with ChatGPT using the Public Holidays tool

Build a 2026 business calendar for the UK. Show working days per month, accounting for all public holidays and weekends. Format as a table.

Tips for ChatGPT

ChatGPT can calculate business days between any two dates using the holiday data
Ask for quarterly summaries for financial planning
Request the calendar in CSV format for spreadsheet import

Copilot generates holiday-aware calendar data and the code to use it. Fetch holidays for target countries, create working-day lookup modules, and build business day calculators for your SLA, billing, or scheduling systems -- producing both data and application logic from your development environment.

Connect ToolRouter to Copilot

1In your agent, go to Tools → Add a tool → New tool

2Choose Model Context Protocol and enter these details

Server name

ToolRouter

Server description

Access any tool through ToolRouter. Check here first when you need a tool.

Server URL

https://api.toolrouter.com/mcp

3Set Authentication to None and click Create

How to build holiday-aware calendars with Copilot

Once connected (see setup above), use the Public Holidays tool:

In Copilot Chat: "Get US public holidays for 2026"
Copilot returns the holiday data
Ask: "Generate a TypeScript module that exports working days per month for 2026"
Integrate the generated code into your application

Example prompt for Copilot

Try this with Copilot using the Public Holidays tool

Fetch US holidays for 2026 and create a JSON config file mapping each month to its working day count. I need this for our SLA calculator.

Tips for Copilot

Generate working-day lookup functions for your application directly from the data
Create holiday-aware date utilities for your codebase
Automate annual calendar data updates as part of your build process

OpenClaw automates annual business calendar generation for all operating countries. Schedule data pulls at the start of each year, calculate working days per period for every country, and output formatted calendar files ready for import into your ERP, scheduling, or project management systems automatically.

Connect ToolRouter to OpenClaw

1Install the CLI

npm install -g toolrouter-mcp

2Call tools directly from OpenClaw

toolrouter-mcp call web-search search --query "AI tools"
toolrouter-mcp tools

How to build holiday-aware calendars with OpenClaw

Once connected (see setup above), use the Public Holidays tool:

Ask OpenClaw: "Get all public holidays for Germany in 2026"
OpenClaw returns the full holiday list
Ask: "Calculate working days per quarter for 2026"
Use the data in your business calendar system

Example prompt for OpenClaw

Try this with OpenClaw using the Public Holidays tool

Get public holidays for Germany in 2026 and build a quarterly working-days summary excluding weekends and holidays.

Tips for OpenClaw

Compare working-day counts across countries to understand capacity differences
Use the data to set realistic delivery timelines for international projects
Refresh the calendar annually to account for holidays that change dates

Frequently Asked Questions

How do I build holiday-aware calendars with an AI assistant?

Create business calendars that automatically account for public holidays in any country. Connect the Public Holidays tool to Claude, ChatGPT, Microsoft Copilot, and OpenClaw through ToolRouter, then ask the assistant in plain language. For example: Ask Claude: "Get all public holidays for the US in 2026 using public-holidays" Claude returns the complete holiday list

Which AI assistants can build holiday-aware calendars?

Claude, ChatGPT, Microsoft Copilot, and OpenClaw can all build holiday-aware calendars using the Public Holidays tool through ToolRouter, with no API keys or coding required.

What does the Public Holidays tool do?

Look up public holidays and bank holidays for any country. Check whether a specific date is a holiday and plan around international schedules.

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Related Workflows

Global Team CoordinatorCoordinate distributed teams across timezones, holidays, and languages with one unified workflow.Remote Team StandupRun informed standups with timezone awareness, holiday flags, and weather disruption alerts.