jsvat
Check the validity of the format of an EU VAT number
au-bn-validator
Validates Australian Business Number (ABN), Australian Company Number (ACN), Australian Registered Body Number (ARBN), Australian Tax File Number (TFN) & Australian Medicare Number
jsvat-next
Check the validity of the format of an EU VAT number
sales-tax
International sales tax calculator for Node (offline, but provides optional online VAT number fraud check). Tax rates are kept up-to-date.