Baidu offers a powerful and free OCR API (百度OCR文字识别API). This project is a basic OCR API test app as Visual Studio C# project.
The source code also serves as English language API documentation. The original Chinese API documentation is at http://apistore.baidu.com/apiworks/servicedetail/146.html
More information and a screencast of the OCR test app in action at http://blog.a9t9.com/2015/09/baidu-ocr-api.html