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/472353970
kbo.party/api/v1/enterprise/998001128
kbo.party/api/v1/enterprise/921409532
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2144466793
kbo.party/api/v1/establishment/2012169384
kbo.party/api/v1/establishment/2153025460