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/228413323
kbo.party/api/v1/enterprise/500004415
kbo.party/api/v1/enterprise/736470322
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2076844432
kbo.party/api/v1/establishment/2117433883
kbo.party/api/v1/establishment/2093845661