Hi Tim,
Really nice. You can take a look at:
http://results.openaddresses.io/coverage/world/
They have a lot of countries covered already, per country they mention the source where they gathered the data.
Regards,
The United States Postal Service has an API for address verification
https://www.usps.com/business/web-tools-apis/welcome.htm
Take a look at:
http://www.geonames.org/datasources/
The Canadian postal service has an address lookup API which is comprehensive. It does have a license requirement for higher volume requests:
https://www.canadapost.ca/cpotools/apps/drc/home?execution=e1s1
Thanks guys for your help. Now I have placed my app in the appstore for everyone to use. And of course to add and improve.
Appname: PostalCodeHousenumber
Local database works, NL works, Canada and US are not yet implemented, but set up. And several ideas and features to add.