I have a task to validate addresses entered into a system I am currently creating. The system requires that address entered are validated against a valid data source. In the UK the dataset comes from the Royal Mail and is expensive to access.

The data needed is post code info for the whold of europe to start with accessed by an API into the web application.

There are a number of companies that offer this service,

1. QAS
2. Capscan
3. Postcode anywhere

These all offer the service I require. However this is expensive and in some cases not a complete data set. e.g. not Ireland

I was also wondering if there would be a way to utalis the google maps API to validate this data via postal code and country.

Would the google maps method be possible or do I have to go down the line of one of these expensive companies? Any thoughts on what line I should take.