aria-mcp-helligdage-dk

A Model Context Protocol (MCP) server exposing Danish public holidays (helligdage) and notable days (mærkedage/flagdage) to AI assistants. Built for ARIA and shareable with the community.

Fully keyless — public holiday data comes from the open nager.date API; notable days are computed in-house.

Data Sources

Source	What	Attribution
nager.date	Official Danish public holidays (helligdage)	nager.date — Open Public Holidays API
In-house computation	Movable and fixed notable days (mærkedage/flagdage)	Anonymous Gregorian algorithm (computus)

Store bededag note

Store bededag (General Prayer Day, 4th Friday after Easter) was a Danish public holiday until 2023. It was abolished as a public holiday from 2024 onwards. get_notable_days still includes it as a mærkedag — not a fridag — with a note, so ARIA can mention it when relevant.

Install & Run

npx aria-mcp-helligdage-dk

Or install globally:

npm install -g aria-mcp-helligdage-dk
aria-mcp-helligdage-dk

Requires Node.js 20 or later.

Tools

get_holidays

Returns all official Danish public holidays (helligdage) for a given year, fetched live from nager.date.

Parameters:

Name	Type	Default	Description
year	number	current year (Europe/Copenhagen)	Year to fetch holidays for

Returns: Array of { date: "YYYY-MM-DD", name: string (Danish), isPublicHoliday: true }

Example output (2026):

[
  { "date": "2026-01-01", "name": "Nytårsdag", "isPublicHoliday": true },
  { "date": "2026-04-02", "name": "Skærtorsdag", "isPublicHoliday": true },
  { "date": "2026-04-03", "name": "Langfredag", "isPublicHoliday": true },
  { "date": "2026-04-05", "name": "Påskedag", "isPublicHoliday": true },
  { "date": "2026-04-06", "name": "2. påskedag", "isPublicHoliday": true },
  { "date": "2026-05-14", "name": "Kristi himmelfart", "isPublicHoliday": true },
  { "date": "2026-05-24", "name": "Pinsedag", "isPublicHoliday": true },
  { "date": "2026-05-25", "name": "2. pinsedag", "isPublicHoliday": true },
  { "date": "2026-06-05", "name": "Grundlovsdag", "isPublicHoliday": true },
  { "date": "2026-12-25", "name": "Juledag", "isPublicHoliday": true },
  { "date": "2026-12-26", "name": "2. juledag", "isPublicHoliday": true }
]

---

is_holiday

Check whether a specific date is an official Danish public holiday.

Parameters:

Name	Type	Default	Description
date	string	today (Europe/Copenhagen)	Date in YYYY-MM-DD format

Returns: { date: "YYYY-MM-DD", isHoliday: boolean, name?: string }

---

next_holidays

Returns the next upcoming Danish public holidays from today.

Parameters:

Name	Type	Default	Description
count	number	5	Number of upcoming holidays to return (max 20)

Returns: Array of { date, name, isPublicHoliday: true }, nearest first.

---

get_notable_days

Returns computed Danish notable days (mærkedage/flagdage) for a given year. These are not public holidays (isPublicHoliday: false).

Parameters:

Name	Type	Default	Description
year	number	current year (Europe/Copenhagen)	Year to compute notable days for

Returns: Array of { date, name, isPublicHoliday: false, note? }, sorted by date.

Included days:

• Fastelavn — 7 weeks (49 days) before Easter Sunday
• Palmesøndag — Sunday before Easter
• Store bededag — 26 days after Easter (abolished as public holiday from 2024; included as mærkedag with note)
• Mors dag — 2nd Sunday of May
• Grundlovsdag / Fars dag — 5 June (also a public holiday; noted as such)
• Sankt Hans aften — 23 June
• Mortensaften — 10 November
• Juleaften — 24 December
• Nytårsaften — 31 December

Movable dates (Easter-based) are computed via the Anonymous Gregorian algorithm, accurate for any year.

---

ARIA Configuration

Add to your ARIA MCP configuration:

{
  "mcpServers": {
    "helligdage-dk": {
      "Command": "npx",
      "Args": ["-y", "aria-mcp-helligdage-dk"]
    }
  }
}

License

MIT — Kim Hjort