WOZ value API for Dutch properties
Get the official Dutch WOZ property value, BAG address data and cadastral parcels for any Dutch address in a single JSON response. Self-serve: create an account, generate a key and make your first call in minutes.
Liever Nederlands? Bekijk de Nederlandse versie.
What is the WOZ value?
The WOZ value (Waardering Onroerende Zaken) is the official property value that every Dutch municipality determines annually for every property. It drives property tax, part of income tax and the water authority levy, which makes it the closest thing the Netherlands has to an official valuation of a home.
Two things matter when you build on it. First, the value lags: a 2026 WOZ value has a reference date of 1 January 2025, so it reflects the market a year earlier. Second, only residential properties are published openly; commercial properties are not.
Curious how these values develop across the country? We publish the average WOZ value per province and municipality from open CBS data, including a downloadable dataset.
Is there an official WOZ API?
Short answer: not one you can use commercially.
| Route | Who can use it | What it takes |
|---|---|---|
| WOZ API Bevragen (Kadaster) | Organisations with a statutory task | OIN plus PKIoverheid certificate |
| WOZ-waardeloket | Anyone | A public website, no API |
| WozApi | Developers and data teams | Sign up, get 10 free credits, call the API |
Where these claims come from
Dutch law sets up the national WOZ facility to serve designated recipients, and separately to feed a public counter. Article 37aa of the Wet waardering onroerende zaken reads:
“een geautomatiseerde landelijke voorziening WOZ met als doel waardegegevens met bijbehorende temporele en meta-kenmerken te verstrekken aan de afnemers, alsmede het op regelmatige basis verstrekken van waardegegevens inzake onroerende zaken die hoofdzakelijk tot woning dienen aan een loket voor openbare WOZ-waarden”
In plain English: an automated national WOZ facility that supplies value data to designated recipients, and regularly supplies residential values to a public counter. Those recipients are municipalities, water authorities and the tax administration; public bodies with a statutory task; and, as a third group, insurers, mortgage lenders and valuation institutes certified by NRVT. If you are not one of them you cannot connect, paid or otherwise. For the Kadaster's WOZ API Bevragen specifically, an active OIN and a PKIoverheid certificate are mandatory.
Scale, for context: the Waarderingskamer, the Dutch WOZ regulator, counts 9.5 million WOZ objects valued for 2026 with 1 January 2025 as the reference date. Residential values rose 10.6 percent on average that year, non-residential 4.1 percent, and in April 2026 some 2.5 percent of homes were under objection. Across the country the average home went from EUR 250,000 in 2019 to EUR 439,000 in 2026, a rise of 75.6 percent.
- Article 37aa, Wet waardering onroerende zaken
- Kadaster, WOZ for recipients and WOZ API Bevragen
- Waarderingskamer, WOZ in figures
- Statistics Netherlands, table 85036NED (CC BY 4.0)
All sources checked on 20 September 2026.
One call, three registries
- WOZ values for every available reference date, so you get the history and not just the latest figure.
- BAG address data: the official Dutch registry of addresses and buildings, including construction year and surface area.
- Cadastral parcels with surface area, and parcel boundaries as GeoJSON when you ask for them.
Client libraries for Python, Node.js and .NET are available on GitHub, the technical documentation is at wozapi.github.io, and the machine readable definition lives in the Swagger documentation. No developer on the team? The Excel wizard enriches a spreadsheet of addresses without writing any code.
Try it with your own addresses
A free account comes with 10 credits. No credit card, no sales call.