The Food PHP SDK is available for download as a zipfile from the Software Development Kits Food webpage. Developers can find the API with endpoints on Mashape at https://market.mashape.com/spoonacular/recipe-food-nutrition
Food-sharing mobile photo app Foodspotting had an API since day one. Of course, every mobile app has an API, at least if it needs to store or retrieve non-trivial data. Most of those interfaces stay hidden away, private APIs with only that single, internal audience. Foodspotting, on the other hand, signed Zagat as an early partner and now also has OpenTable, among others, using its Foodspotting API. The company is not exactly making it widely available for any developer, though the documentation is public, planting it in a vast grey area that's becoming increasingly common.
Covering over 200,000 foods and dishes, MyNetDiary's API provides two services to integrate right into your application: FindFood ( 0.5 cents a query) and GetFoodDetails. The input format is HTP request parameters or SOAP. Output format is JSON or SOAP. Food lookup results are sorted by popularity.