Launching the Aggregator API: What We Built and Why

Today we are publicly launching the Voseno Aggregator API. It provides a single, normalized feed of Dutch residential property listings from over 1,400 sources, covering every municipality in the Netherlands.

The problem

Every PropTech company operating in the Netherlands builds some version of the same data pipeline. They scrape listing portals, normalize inconsistent schemas, handle deduplication across sources, and then spend ongoing engineering time maintaining it all as sites change their markup. This work is expensive, fragile, and has nothing to do with the actual product these companies are trying to build.

The Dutch listing landscape is unusually fragmented. Funda dominates sales but is restricted to NVM members. Pararius covers a large share of the rental market. Jaap.nl, Huislijn, and hundreds of independent broker websites each carry listings that may not appear elsewhere. A single apartment in Utrecht can appear on eight different portals simultaneously, each with slightly different data.

What the API does

• Aggregates listings from 1,400+ monitored Dutch property sources, both sale (koopwoningen) and rental (huurwoningen)
• Normalizes all data into a consistent schema: property type, address components, pricing, surface area, room count, source metadata
• Deduplicates cross-source listings using BAG ID resolution, fuzzy address matching, and feature fingerprinting
• Links every listing to its BAG verblijfsobject ID where resolvable via the PDOK geocoder
• Targets sub-5-minute freshness from source publication to API availability
• Provides search, filtering, pagination, and webhook-based notifications for new and updated listings

A quick example

Search for rental listings in Amsterdam under €2,000/month:

curl -G "https://api.voseno.com/v1/listings/search" \
  -H "Authorization: Bearer vos_live_..." \
  --data-urlencode "city=Amsterdam" \
  --data-urlencode "type=rental" \
  --data-urlencode "max_price=2000"

The response returns a paginated list of deduplicated listings, each with normalized fields, the original source URL, and the BAG verblijfsobject ID when available.

Coverage

The API covers all 342 Dutch municipalities. Sources range from national portals like Funda and Pararius to regional broker networks and individual makelaar websites. We monitor source availability continuously, and new sources are added as we discover them.

What is next

The Aggregator API is the first of four planned data products. Next is the Property API: a comprehensive record for any Dutch address, combining BAG registration data, WOZ valuations, energy labels from EP-Online, and Kadaster transaction history. We are building toward a complete Dutch property data platform so that developers can focus on their products instead of their data pipelines.

Interested in access? Request a demo at voseno.com to see the API in action.