If you are looking for an API which provides context related data on the following go and have a look at Factual API.
1. Healthcare Providers Data (Currently only in US)
2. Restaurants data including cuisine, pricing, rating
3. Hotels data including price, guest rating
4. World geographies data
After you get the key you can use any of the following tools to access the API. There is a C# version of API with examples as well available now.
- First Release of Factual C# / .NET Driver (factual.com)
- Factual Aims to be Framework for Local Offers (programmableweb.com)
- How the Data Stack Can Organize Your Data Science Program (factual.com)