So I implemented an address validation using Google maps API and looking for some dataset of valid addresses for testing. I already used Openaddreses data which is great and covers lots of countries, but for some countries ( Like Slovakia, Romania, Portugal, Estonia ) only 3 percent of data had valid addresses.
I was wondering if anyone here had implemented an address validation before and let me know what kind of data source do you used for testing, I prefer if it's free service but if it's even a paid service, I appreciate it if you can let me know.