Google: Places API
Google Places API is free for low volume usage. There are several ways to use the API. Typically for businesses it’s used to show the location of the business to enable customers to find them. There is more data available when using it, which is used to find the review level of the location. Also the discovery other businesses by location and taxonomy; This proves to be a powerful tool for the social media marketeer.
For businesses looking to find vendors for their good, this is a goldmine of information; Enabling companies to find distributors with ease. This is just but one application of this great little tool, and if you need volume you’ll end up paying per requests (though their initial limits are very generous).
I’ve used this API in conjunction with social media API and a CRM to collate information useful to businesses that need to expand, and don’t want to pay for social media advertising. Very easy to implement.
When you need either a visual map for website visitors, or to access the masses of map data held publically by Google.
It’s not free when you scale up.