Address autocomplete API

# Danish address suggestions, as the user types

An address field that suggests real Danish addresses from the second keystroke. It forgives typos and half-typed street names, and every suggestion carries a stable address ID — so the choice can go straight on to the property behind it.

The calls

- [GET /v1/autocomplete](https://grundfast.dk/docs/api/autocomplete)
- [GET /v1/adresse/search](https://grundfast.dk/docs/api/adresse-search)

[Get started free](https://grundfast.dk/dashboard?mode=register) [Read the API reference](https://grundfast.dk/docs/api)

[Læs denne side på dansk](https://grundfast.dk/adresse-autocomplete-api)

Try it

## Misspell a street name

The box opens on “Vestrebrogade 10” — a typo — and still finds Vesterbrogade in five towns. Type any Danish address to search the live register.

Real results · type any Danish address

- Vesterbrogade 10, 8800 Viborg 0a3f5098-fed5-32b8-e044-0003ba298018 BFE 5588347
- Vesterbrogade 10, 4930 Maribo 0a3f5085-7d1d-32b8-e044-0003ba298018 BFE 5414863
- Vesterbrogade 10, 6000 Kolding 0a3f5090-66bb-32b8-e044-0003ba298018 BFE 8069127
- Vesterbrogade 10, 7200 Grindsted 0a3f508e-0a9a-32b8-e044-0003ba298018 BFE 5138843
- Vesterbrogade 10, 8000 Aarhus C 0a3f5097-2080-32b8-e044-0003ba298018 BFE 5623355

`GET /v1/adresse/search` — here through its keyless demo, capped at six hits.

Prefix matches rank first, then matches by similarity. Danish letters can be typed the way a non-Danish keyboard allows: _ae_, _oe_ and _aa_ find æ, ø and å.

The demo calls the keyless `/v1/demo/adresse-search`, the same search service as the keyed endpoint. Each hit shows its **BFE number** — the national ID of the property the address sits on, and the key to its buildings, parcels and valuation.

The answer

## Text to show, a value to store

Each suggestion has `tekst` for the list and `vaerdi` as the key — the address UUID, a street name or a postcode, depending on `type`. The field names are the register’s own Danish terms.

GET /v1/autocomplete?q=rådhuspladsen+1550 json

```
{
  "type": "adgangsadresse",
  "antal": 3,
  "resultater": [
    {
      "type": "adgangsadresse",
      "tekst": "Rådhuspladsen 1, 1550 København V",
      "vaerdi": "0a3f507a-ec01-32b8-e044-0003ba298018"
    },
    {
      "type": "adgangsadresse",
      "tekst": "Rådhuspladsen 2, 1550 København V",
      "vaerdi": "39ece5fb-ee06-0ee2-e044-0003ba298018"
    },
    {
      "type": "adgangsadresse",
      "tekst": "Rådhuspladsen 3, 1550 København V",
      "vaerdi": "0a3f507a-ec03-32b8-e044-0003ba298018"
    }
  ]
}
```

| Field | Contents |
| --- | --- |
| antal | Number of suggestions, at most 20. |
| resultater[].tekst | The line to show, e.g. “Rådhuspladsen 1, 1550 København V”. |
| resultater[].vaerdi | The key to store: the UUID of the unit or access address, the street name or the postcode. |

| Parameter | Description |
| --- | --- |
| q | The text typed so far, at least 2 characters. Typos still match, and ae / oe / aa are read as æ / ø / å. |
| type | adgangsadresse (default), adresse, vejnavn or postnummer. “adresse” walks from street to house number to floor and door; every hit carries its own type. |
| adgangsadresseid | Only with type=adresse: a chosen access address — the answer is its units, with floor and door. |
| kommunekode | Limits street names to one municipality, e.g. 0101. |

Build the field

## Debounce, abort, show the text, store the value

A good address field is four rules: wait for a pause in typing, abort the previous request, show tekst in the list, and store vaerdi — never the text.

address-field.js javascript

```
// An address field with suggestions — one call per pause in typing, not per letter.
// /api/addresses is your own backend, which calls /v1/autocomplete with the key.
const input = document.querySelector('#address');
const list = document.querySelector('#suggestions');
let timer, ctrl;

input.addEventListener('input', () => {
  clearTimeout(timer);
  const q = input.value.trim();
  if (q.length < 2) return list.replaceChildren();
  timer = setTimeout(async () => {
    ctrl?.abort(); // the newest keystroke always wins
    ctrl = new AbortController();
    const res = await fetch('/api/addresses?q=' + encodeURIComponent(q), {
      signal: ctrl.signal,
    });
    const { resultater } = await res.json();
    list.replaceChildren(
      ...resultater.map((hit) => {
        const li = document.createElement('li');
        li.textContent = hit.tekst; // what the user sees
        li.dataset.uuid = hit.vaerdi; // what you store
        return li;
      }),
    );
  }, 150);
});
```

Call the API from your own backend so the secret key never reaches the browser — or create a publishable `gf_pub_live_` key locked to your domains. With a 150 ms debounce a field typically sends three or four calls per address.

Coming from DAWA’s `/autocomplete`? The request is the same, but the answer is wrapped in `{ type, antal, resultater }`. The [DAWA replacement guide](https://grundfast.dk/en/dawa-replacement) maps every endpoint.

Call it

## One endpoint for addresses, streets and postcodes

Same key and the same response shape as the rest of the API. The TypeScript SDK aborts a stale request for you when you pass it a signal.

```
import { GrundfastClient } from '@grundfast/sdk';

const gf = new GrundfastClient({ apiKey: 'gf_live_…' });

let inFlight: AbortController | undefined;

export async function suggest(q: string) {
  inFlight?.abort(); // a newer keystroke overtakes the previous answer
  inFlight = new AbortController();
  const { resultater } = await gf.autocomplete(q, 'adgangsadresse', undefined, {
    signal: inFlight.signal,
  });
  return resultater; // [{ type, tekst, vaerdi }] — show tekst, store vaerdi
}
```

npm i @grundfast/sdk

FAQ

## Questions about address autocomplete

### What is an “adgangsadresse”?

Danish addresses come in two levels. An adgangsadresse (access address) is a street, house number and postcode — the door you walk up to. An adresse adds floor and door for a single flat or office inside it. Autocomplete suggests access addresses by default; with type=adresse it continues down to the unit.

### How fast is it?

Suggestions come from Grundfast’s own index of the whole Danish address register (DAR), not from a call upstream per keystroke, so the latency is our database plus the network between you and it. The demo on this page shows the measured round trip from your own browser.

### Should I call it on every keystroke?

On every pause instead. Wait 100–200 ms after the last keystroke and abort the previous request when a new one starts. An address then costs three or four calls instead of twenty, and a slow answer can never overwrite a newer one.

### Can I call it straight from the browser?

Yes, with a publishable key (gf_pub_live_…). It only opens the address endpoints a form needs, only answers requests from the domains you list in the dashboard, and has a per-visitor rate limit. A secret `gf_live_` key belongs on your server.

### What is the difference between /v1/autocomplete and /v1/adresse/search?

`/v1/autocomplete` returns a light list of tekst and vaerdi and can also suggest street names and postcodes. `/v1/adresse/search` returns the full address for each hit — street, number, postcode, municipality code, coordinate and BFE number — and is what you use when the choice has to continue to the property.

### What does an address field cost?

Every request counts as one call, including the ones a field sends while someone types — which is why debouncing pays. The Free plan includes 5,000 calls a month and Starter 100,000. A `gf_test_` key gives free test calls for development that are never billed.

See also

- [Danish address API](https://grundfast.dk/en/address-api)
- [Reverse geocoding API](https://grundfast.dk/en/reverse-geocoding-api)
- [DAWA replacement](https://grundfast.dk/en/dawa-replacement)
- [Pricing](https://grundfast.dk/en/pricing)

## Put suggestions on your address field today

Create a free key and make your first call in a minute. Build against a `gf_test_` key that is never billed, and upgrade when the traffic is real.

[Get started free](https://grundfast.dk/dashboard?mode=register) [Read the API reference](https://grundfast.dk/docs/api)

Free up to 5,000 calls a month · no card · test keys never billed · data from Klimadatastyrelsen / Datafordeler, CC BY 4.0