In countries that have a tax agreement with Germany (e.g. Canada), the Reverse Charge procedure is used; you signalise that on your invoice. In that case, the customer is obligated to pay the VAT in their country and you bill the net amount. However, that depends on the service/product sold. If you re-sell development services, for example, you still have to pay VAT in Germany on a part of the amount billed while the rest is covered by Reverse Charge.