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/589543333
kbo.party/api/v1/enterprise/729035964
kbo.party/api/v1/enterprise/877940862
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2067591523
kbo.party/api/v1/establishment/2194293418
kbo.party/api/v1/establishment/2243111736