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/521491596
kbo.party/api/v1/enterprise/531032834
kbo.party/api/v1/enterprise/890618564
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2021143567
kbo.party/api/v1/establishment/2212327894
kbo.party/api/v1/establishment/2209837766