Dutch postcode API — verrijk een postcode + huisnummer met BAG-metadata, WGS84-coördinaten en energielabel. BAG address API JSON via Kadaster.

GET /v1/geo/address-enrich

Enriches a Dutch postcode and house number with official BAG (Basisregistratie Adressen en Gebouwen) address data and optionally the registered EP-Online energy label.

Data flow:

PDOK Locatieserver (free) — geocode to nummeraanduiding_id + WGS84 coordinates
Kadaster BAG Individuele Bevragingen v2 — fetch address details, surface area, building year
EP-Online v5 (optional) — fetch registered energy label

Request parameters

Parameter	Type	Required	Default	Description
`postcode`	string	✓	—	Dutch postcode, e.g. `1234AB` or `1234 AB`
`house_number`	string	✓	—	House number, e.g. `42`
`energy`	boolean		`true`	Include EP-Online energy label when available

Example request

curl -H "X-API-Key: YOUR_KEY" \
  "https://api.omnizoek.nl/v1/geo/address-enrich?postcode=1012LG&house_number=1"

Example response

{
  "street": "Damrak",
  "house_number": "1",
  "house_letter": null,
  "house_addition": null,
  "postcode": "1012LG",
  "city": "Amsterdam",
  "municipality": "Amsterdam",
  "province": "Noord-Holland",
  "lat": 52.3756,
  "lon": 4.8951,
  "bag_id": "0363010000000001",
  "surface_m2": 120,
  "building_year": 1920,
  "usage_function": "woonfunctie",
  "status": "Verblijfsobject in gebruik",
  "energy_label": "C",
  "energy_label_registered": "2021-03-15",
  "energy_label_valid_until": "2031-03-15",
  "energy_label_calculation_type": "Nader Voorschrift"
}

Response fields

Field	Type	Description
`street`	string	Street name (`openbareRuimteNaam`)
`house_number`	string	House number
`house_letter`	string \| null	House letter suffix (e.g. `A`)
`house_addition`	string \| null	House number addition (e.g. `bis`)
`postcode`	string	Normalised postcode (no spaces)
`city`	string	City (`woonplaatsNaam`)
`municipality`	string \| null	Municipality (`gemeenteNaam`)
`province`	string \| null	Province (`provincieNaam`)
`lat`	number \| null	Latitude in WGS84
`lon`	number \| null	Longitude in WGS84
`bag_id`	string	BAG adresseerbaar object identifier
`surface_m2`	integer \| null	Floor area in square metres
`building_year`	integer \| null	Year of construction
`usage_function`	string \| null	Primary use function (e.g. `woonfunctie`)
`status`	string \| null	BAG registration status
`energy_label`	string \| null	Energy class (A+++…G) — `null` when not registered
`energy_label_registered`	string \| null	Registration date (YYYY-MM-DD)
`energy_label_valid_until`	string \| null	Expiry date (YYYY-MM-DD)
`energy_label_calculation_type`	string \| null	Calculation method

Error responses

Status	Error code	Cause
`404`	`address_not_found`	Postcode + house number not found in PDOK or BAG
`503`	`bag_api_error`	Kadaster BAG API unavailable
`503`	`environment_error`	`BAG_API_KEY` not configured on server

Caching

Responses are cached in RAM for 24 hours keyed on {postcode}_{house_number}.

Address Enrichment (BAG)