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Date Calculator

Official registry Other

Count days between dates, add or subtract dates, and look up public holidays by country.

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (streamable-http)
Claude Code 
claude mcp add --transport http date-calculator 'https://mcp.onlinealarmkur.com/'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "date-calculator": {
            "type": "http",
            "url": "https://mcp.onlinealarmkur.com/"
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. Date Calculator
  2. Tools
  3. Connect
  4. Example prompts
  5. Limits
  6. Support

Date Calculator

An MCP server for date calculations and public holidays, using the same date calculator created by Online Alarm Kur.

This repository contains documentation and registration metadata for the hosted service.

  • Endpoint: https://mcp.onlinealarmkur.com/
  • Transport: Streamable HTTP
  • Authentication: None
  • Documentation: mcp.onlinealarmkur.com

Tools

ToolWhat it does
count_daysCount days between two dates, optionally excluding selected weekdays and public holidays.
shift_dateAdd or subtract years, months, weeks and days, with optional weekday and holiday exclusions.
get_holidaysList public holidays, including observed dates, for a country and optional region, for up to 11 years per request.
list_locationsFind supported countries, regions and available years.

Dates use the Gregorian calendar in YYYY-MM-DD format, without a time of day. Weekends and holidays are included unless explicitly excluded.

Date calculation results include the rules used and a share link that opens the same calculation on the website. Calculation and holiday tools accept the website's 32 languages; holiday names may fall back to their native language.

Connect

Claude
  1. Open Customize, then Connectors.
  2. Select + Add, then Add custom connector.
  3. Enter Date Calculator as the name and https://mcp.onlinealarmkur.com/ as the URL, then select Continue.
  4. Under Authentication, choose No sign in, then select Add.

On Team and Enterprise plans, an organization owner adds the connector first; members then connect it. See Anthropic's custom connector instructions.

Claude Code
claude mcp add --transport http date-calculator https://mcp.onlinealarmkur.com/
Cursor

Add this entry to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "date-calculator": {
      "url": "https://mcp.onlinealarmkur.com/"
    }
  }
}
VS Code

Add this entry to .vscode/mcp.json:

{
  "servers": {
    "date-calculator": {
      "type": "http",
      "url": "https://mcp.onlinealarmkur.com/"
    }
  }
}

If the configuration file already contains other servers, add the entry to the existing object.

ChatGPT

Where your account and workspace allow custom MCP connections:

  1. Open ChatGPT Plugins in your browser.
  2. Select the plus button, then Add custom MCP server.
  3. Enter Date Calculator as the name and https://mcp.onlinealarmkur.com/ as the server URL. Choose no authentication.
  4. Review the permissions and warning, then select Create as a plugin.
  5. Install the resulting plugin, start a new conversation and select it using @.

See OpenAI's custom MCP server instructions.

Grok
  1. Open Grok Connectors.
  2. Select New Connector, then Custom.
  3. Enter https://mcp.onlinealarmkur.com/ as the MCP server URL. No authentication is required by this server.
  4. Complete the setup to make the tools available in conversations.

For Grok Business and Enterprise, a team admin must first add the connector for the organization.

See Grok's connector documentation.

Other MCP clients

Where custom remote MCP connections are available, use https://mcp.onlinealarmkur.com/ with Streamable HTTP and no authentication. See the connection instructions.

Example prompts

  • "How many working days are there between 2 November and 24 December 2026 in Germany, excluding Saturdays, Sundays and public holidays?"
  • "What date is 90 days after 15 January 2027?"
  • "List the public holidays in Turkey for 2027."

Limits

Rate limits apply. Holiday lookups share a daily budget; if it is exhausted, holiday features pause until 00:00 UTC. Calculations without holidays remain available.

Future holiday dates can change. Check important deadlines with the relevant authority.

Support

For bug reports and questions, open an issue. Report security problems privately with Report a vulnerability.

Frequently asked questions

What is Date Calculator?

Count days between dates, add or subtract dates, and look up public holidays by country.

How do I install Date Calculator?

It runs as a remote server. In Claude Code: claude mcp add --transport http date-calculator 'https://mcp.onlinealarmkur.com/'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does Date Calculator need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is Date Calculator open source?

Its code is public on GitHub, but the repository does not declare a standard license.

Who maintains Date Calculator?

It is published by onlinealarmkur. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.