We need a WAF for our Webservice which we are developing at the moment and I'm not sure if we should use FrontDoors or an ApplicationGateway. For the start, we plan to offer our service just for Europe, so in this case FrontDoors is not necessary right? But in the future (maybe 1 year after release) we also want to offer the service e.g. in the US, so in this case we could need FrontDoors.
So my question is: Should we use FrontDoors now in mind we need it later, even if we don't use all of the functionality and I think FrontDoors is quite expensive or is it worth to use ApplicationGateway for the start? Is it possible to migrate WAF from Gateway to FrontDoors?
Its not possible to use WAF standalone or is it?