- requires an API key
- http geocode service that'll return results in XML or JSON
- issues in resolving bad addresses by suggesting alternatives and flagging them with the best accuracy-level
- comma separated values on the query string
- 50k per day limit
- http geocode service return results in XML or PHP
- cleaner documentation
- ApplicationID required
- address suggestion behaves more as expected and accuracy seems better
- query string attributes expected in request
- 5k per day limit
Note regarding accuracy statements above: I tested both services with variations on my home address which can be identified strictly by number coordinates or with the street name (Valley Sage Drive). Google's service did not find my address in any format I tried but continued to respond with varied suggestions none of which were applicable (though it stated they were the highest level of accuracy). As for yahoo, it found my address in every variation and for those that it suggested it clearly indicated a warning as an attribute of the ResultSet. Odd that Google Maps works for my address, but the geocoding service does not (and they're supposed to be integrated).
Both services provide city and state values when given a zip.
Determining valid addresses may prove to be a bit difficult given that both services "suggest" what the closest match could be.