Datafordeler Dar MCP Server

datafordeler-dar-mcp

MCP server for Danish addresses from Danmarks Adresseregister (DAR) on Datafordeleren, the official national data distributor.

DAWA (dawa.aws.dk, api.dataforsyningen.dk) closed on 1 October 2026 and now returns HTTP 410. Every address tool that was built on it is dead. Klimadatastyrelsen's replacement is Datafordeleren, which is keyed, bitemporal and GraphQL-first. This server gives AI agents (Claude, Cursor, VS Code, any MCP client) the DAR data through ten small, documented tools, with the coordinates converted to WGS84 and the DAR UUIDs that DAWA also used.

Status: v0.1, a probe. It exists to find out whether anyone wants a maintained MCP layer over Danish public data. Stars, npm downloads and issues are the signal. It is deliberately thin: no caching, no metering, one source.

What it does

Every result carries attribution (CC BY 4.0, Klimadatastyrelsen), DAR status codes with English labels, and points in both EPSG:25832 and WGS84. Errors are typed (config, bad_request, auth, not_found, rate_limited, upstream, timeout, network) and say what to do next.

Install

Requires Node.js 20 or newer.

Claude Code:

claude mcp add datafordeler-dar -- npx -y datafordeler-dar-mcp

Claude Desktop, Cursor, VS Code and other clients (mcp.json / claude_desktop_config.json):

{
  "mcpServers": {
    "datafordeler-dar": {
      "command": "npx",
      "args": ["-y", "datafordeler-dar-mcp"],
      "env": { "DATAFORDELER_API_KEY": "your-key-here" }
    }
  }
}

Getting an API key, and why you will need one

Anonymous access to the legacy REST service works today, which is why the seven lookup tools need no key. Klimadatastyrelsen has announced that after 15 January 2027 Datafordeleren only serves authenticated requests (API key or OAuth). Text search already needs a key because it runs on the GraphQL service.

1. Create a free account at https://datafordeler.dk (Datafordeler Administration). An e-mail user is enough; MitID Erhverv is optional.
2. Create an IT-system and add an API key to it.
3. Set DATAFORDELER_API_KEY.

No approval step is needed for DAR. A new key takes up to 15 minutes to activate; until then the service answers 401 "Unrecognized Authentication key". Rate limits are not published; the server surfaces HTTP 429 as rate_limited.

Optional legacy credentials (DATAFORDELER_USERNAME, DATAFORDELER_PASSWORD) are passed through to the REST service if set.

Examples an agent can chain

dar_get_postcode({ postcode: "1663" })
  -> postcodes[0].id = d4a3a5ad-...
dar_list_access_addresses({ postcode_id: "d4a3a5ad-...", page_size: 50 })
  -> entrances with lat/lon
dar_list_addresses({ access_address_id: "0a3f507a-d330-32b8-e044-0003ba298018" })
  -> 12 units at Oehlenschlægersgade 35
dar_get_address({ address_id: "0a3f50a0-0000-32b8-e044-0003ba298018" })
  -> "Oehlenschlægersgade 35, st. tv, 1663 København V", municipality 0101, parish Vesterbro

With a key:

dar_search_addresses({ query: "rentemester", level: "street" })
  -> Rentemestervej, København (0101), id 831a760e-...
dar_list_access_addresses({ street_id: "831a760e-4e3f-42e8-a9a5-0b771f72880a" })
  -> every house number on the street, with lat/lon
dar_search_addresses({ query: "Rentemestervej 8, 2400" })
  -> "Rentemestervej 8, 2400 København NV"
dar_search_addresses({ query: "Oehlenschlægersgade 35, st", level: "address" })
  -> st. tv and st. th

What the GraphQL service actually does

Verified against the live service on 2026-10-01. Several points differ from Datafordeleren's published transition guide (v2.3, January 2025):

• DAR is served at /DAR/v2. /DAR/v1, which the guide documents, returns 404.
• Every entity query must carry virkningstid and/or registreringstid, or filter on id_lokalId. Pass both set to now for the current state; with virkningstid alone you also get superseded registrations.
• startsWith exists only on adgangsadressebetegnelse, adressebetegnelse, vejnavn, postnr and navn, and is case-sensitive. Everything else takes eq and in. There is no fuzzy, substring or ranked search, and no autocomplete.
• References are ids. A DAR_Husnummer holds the UUIDs of its street, postcode and access point; coordinates live on DAR_Adressepunkt.
• Field names transliterate æ/ø/å as ae/oe/aa (doerbetegnelse).
• Paging is forward-only: first (max 1000) and after.
• Responses are fast: 30 to 150 ms per query in testing.

dar_search_addresses handles the time arguments, the status filter and the first letter's case for you. dar_graphql passes queries through untouched and returns the service's errors verbatim.

Data, licence and attribution

Source: Danmarks Adresseregister via Datafordeleren, Klimadatastyrelsen. Licence: CC BY 4.0 per Datafordeleren's terms of use. You must credit Klimadatastyrelsen "på et passende sted"; the attribution field in every response is there to be passed on. Addresses are not personal data. The server stores nothing and logs nothing.

Known limits of the legacy REST service this version leans on: no text search, no reverse geocoding, no autocomplete, pagination by page number only, and a scheduled shutdown on 15 January 2027. The replacement for all of those is the GraphQL service behind the three keyed tools.

Development

npm install
npm test          # build + unit tests + stdio integration tests (offline)
npm run test:live # also hits services.datafordeler.dk

With DATAFORDELER_API_KEY set, test:live also exercises the three GraphQL tools; without it those tests are skipped.

Layout: src/client.ts (REST and GraphQL fetch, typed errors), src/normalise.ts (flattening, status labels, UTM32 to WGS84), src/server.ts (tool registrations), src/index.ts (stdio entry point). Tests use fixtures captured from the live service on 2026-10-01.

Feedback

If this is useful to you, or missing something you need (other registers, reverse geocoding, a hosted endpoint), please open an issue. Issues and stars are how this project decides what to build next.

Licence

MIT. See LICENSE.