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/663600556
kbo.party/api/v1/enterprise/550375822
kbo.party/api/v1/enterprise/561025927
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2248066654
kbo.party/api/v1/establishment/2095612249
kbo.party/api/v1/establishment/2259440103