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/998001128
kbo.party/api/v1/enterprise/764002286
kbo.party/api/v1/enterprise/703432914
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2009262255
kbo.party/api/v1/establishment/2074927889
kbo.party/api/v1/establishment/2084065586