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/237684444
kbo.party/api/v1/enterprise/632708234
kbo.party/api/v1/enterprise/654601629
Lookup establishment by VAT id
kbo.party/api/v1/establishment/2057990008
kbo.party/api/v1/establishment/2103990376
kbo.party/api/v1/establishment/2083191695