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/528018906
kbo.party/api/v1/enterprise/400000185
kbo.party/api/v1/enterprise/853662752
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2121443547
kbo.party/api/v1/establishment/2224732018
kbo.party/api/v1/establishment/2233748959