Dutch Address and Building Lookup

Look up a Dutch address in the Kadaster BAG register: street, city, construction year, floor area, use, and national grid coordinates.

nl-bag-address

Example

Example answer

{
  "city": "'s-Gravenhage",
  "street": "Plein",
  "postcode": "2514JK",
  "huisnummer": 1,
  "full_address": "Plein 1, 2514JK 's-Gravenhage",
  "building_type": "Verblijfsobject",
  "floor_area_m2": 250,
  "coordinates_rd": {
    "x": 81491.2,
    "y": 455032.6,
    "crs": "EPSG:28992"
  },
  "usage_purposes": [
    "woonfunctie"
  ],
  "construction_year": "1900"
}

Inputs

Field	Type	Required	What it is
`postcode`	string	Yes	Dutch postcode (format 1234AB)
`huisletter`	string	No	House letter (optional)
`huisnummer`	string	Yes	House number
`toevoeging`	string	No	House number addition (optional)

Output fields

How reliably each field appears in a successful answer.

Field	Type	Appears
`city`	string	Always (present in every successful answer)
`street`	string	Always (present in every successful answer)
`postcode`	string	Always (present in every successful answer)
`huisnummer`	number	Always (present in every successful answer)
`full_address`	string	Always (present in every successful answer)
`floor_area_m2`	number	Usually (present for most inputs)
`construction_year`	string	Usually (present for most inputs)
`nummeraanduiding_id`	—	Always (present in every successful answer)
`adresseerbaar_object_id`	—	Usually (present for most inputs)
`woonplaats_id`	—	Usually (present for most inputs)
`building_type`	—	Usually (present for most inputs)
`usage_purposes`	—	Usually (present for most inputs)
`status`	—	Usually (present for most inputs)
`coordinates_rd`	—	Usually (present for most inputs)
`huisletter`	—	Sometimes (present only for some inputs)
`huisnummertoevoeging`	—	Sometimes (present only for some inputs)
`total_results`	—	Always (present in every successful answer)

How to call it

The same tool through each route. MCP clients reach it through Strale’s server at https://api.strale.io/mcp; the call below is what the agent sends.

# Needs an API key. max_price_cents caps what this call may cost.
curl -X POST https://api.strale.io/v1/do \
  -H "Authorization: Bearer $STRALE_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "capability_slug": "nl-bag-address",
    "inputs": {
      "postcode": "1012JS",
      "huisnummer": "1"
    },
    "max_price_cents": 5
  }'

{
  "tool": "strale_execute",
  "arguments": {
    "slug": "nl-bag-address",
    "inputs": {
      "postcode": "1012JS",
      "huisnummer": "1"
    },
    "max_price_cents": 5
  }
}

import { Strale } from "straleio";

const strale = new Strale({ apiKey: process.env.STRALE_API_KEY! });
const result = await strale.do({
  capability_slug: "nl-bag-address",
  inputs: {
    "postcode": "1012JS",
    "huisnummer": "1"
  },
  max_price_cents: 5,
});

import os
from straleio import Strale, DoRequest

strale = Strale(api_key=os.environ["STRALE_API_KEY"])
result = strale.do(DoRequest(
    capability_slug="nl-bag-address",
    inputs={
        "postcode": "1012JS",
        "huisnummer": "1",
    },
    max_price_cents=5,
))

Limitations

Requires BAG API key
A free API key from Kadaster is required. Register at https://formulieren.kadaster.nl/aanvraag_bag_api_individuele_bevragingen_productie
Dutch addresses only
Only covers addresses registered in the Dutch BAG (Netherlands).

Bundled checks that include it

Netherlands Property Check €0.19