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/500004415
kbo.party/api/v1/enterprise/326379561
kbo.party/api/v1/enterprise/766491129
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2019536535
kbo.party/api/v1/establishment/2064048053
kbo.party/api/v1/establishment/2261631016