KvKBase: Dutch Company Data in One API Call

Every Dutch B2B product eventually needs company data. Verify a KvK number, autofill an address from it, check whether a business still exists. I’d written some version of that lookup more than once, so I built KvKBase properly and made it available to everyone else.

It’s Dutch company data in one API call, with pricing that’s visible on the page rather than hidden behind a sales conversation, which is not the norm in this corner of the market.

The thing worth getting right was the response shape. The way this data exists upstream is not the way an application wants to consume it, so the API returns flat, predictable records instead of passing raw structures through and leaving every developer to untangle the same mess themselves.