Dutch elevation (AHN / NAP height)

$0.006 / call

GET /api/v1/nl/elevation

Ground height above NAP, surface height and derived object height for a Dutch postcode or coordinate, from the AHN 0.5 m height model via PDOK.

Parameters

Name	Required	Description
`postcode`	no	Dutch postcode, e.g. 3511LM (resolved to its centroid).
`lat`	no	WGS84 latitude; use with lon instead of postcode.
`lon`	no	WGS84 longitude; use with lat instead of postcode.
`sample`	no	Query param on GET; set to 1 for the free demo response.

Free sample

curl https://api.agenticweb.nl/api/v1/nl/elevation?sample=1

Paid call

Returns 402 Payment Required; pay over x402 and retry.

curl -X POST https://api.agenticweb.nl/api/v1/nl/elevation \
  -H 'Content-Type: application/json' \
  -d '{"postcode":"3511LM"}'

This endpoint takes its parameters in a JSON request body rather than the query string, because they are personal data and a request URL is recorded in server access logs. A GET without ?sample=1 returns 405.

Licensing

CC0 1.0 (AHN, Rijkswaterstaat, via PDOK); public domain, no attribution required.

Heights are metres relative to NAP, sampled as the median of up to 9 AHN cells within ~3 m of the point. The AHN masks open water, so a point in a canal or river returns nap_m: null with nodata_cells > 0 rather than a wrong number; a point with no data in either layer returns 404. object_height_m (surface minus ground) is a neighbourhood estimate and varies near building edges.