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/930684514
kbo.party/api/v1/enterprise/998001128
kbo.party/api/v1/enterprise/400000185
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2040272165
kbo.party/api/v1/establishment/2022168007
kbo.party/api/v1/establishment/2252808172