api to use for calculating distance between two addressess. (except google api)

what api is the easiest to use in calculating the distance between two addresses using roads not the straight line distance. i would like to use a different api than googles since i heard their api is not for paid apps. i would like the api to be easy to implement and would appreciate 开发者_C百科if that api offered some sample code.

How about Bing Maps API? http://www.bing.com/developers

Actually, you can use google maps/earth for paid apps. In fact, the paid version has more advanced features. But it is quite expensive (to me at least). To quote Google:

Google Maps API Premier is extremely cost-effective, starting at just $10,000 per year. Pricing is based on the number of map page views for externally facing websites. For internal uses, it is based on page views or number of vehicles being tracked.

See the Google enterprise page for details: http://www.google.com/enterprise/earthmaps/index.html

Having looked around it appears that some of the other geospatial software/services are even more expensive. I guess Google is not that expensive compared to everything else in the industry. Apparently TripAdvisor is one of their clients.

It should be noted that Google doesn't prevent you from making money from using Google maps. A lot of real estate agents for example use Google maps to sell houses. You just cannot block the public from using the maps feature on your site - for example requiring a paid login account. A lot of businesses still use the free version of Google maps. The key is, sell other things but make the map feature free.