KBO.party offers the monthly KBO csv export as a REST service.
Free in beta
Lookup company by VAT id
kbo.party/api/v1/enterprise/280300108
kbo.party/api/v1/enterprise/739479104
kbo.party/api/v1/enterprise/306414387
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2129098827
kbo.party/api/v1/establishment/2038273569
kbo.party/api/v1/establishment/2066859469