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/908581083
kbo.party/api/v1/enterprise/777000484
kbo.party/api/v1/enterprise/958759084
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2153282907
kbo.party/api/v1/establishment/2017409661
kbo.party/api/v1/establishment/2152779594