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/960526464
kbo.party/api/v1/enterprise/606245446
kbo.party/api/v1/enterprise/748046875
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2237889671
kbo.party/api/v1/establishment/2122863905
kbo.party/api/v1/establishment/2163439993