From the documentation:
AlchemyAPI utilizes natural language processing technology and machine learning algorithms to analyze content, extracting semantic meta-data: information about people, places, companies, topics, facts & relationships, authors, languages, and more.
API endpoints are provided for performing content analysis on Internet-accessible web pages, posted HTML or text content.
To use AlchemyAPI, you need an access key. If you do not have an API key, you must first obtain one.
I haven’t used it but it looks like a useful service for information products meant for an end user.
Do you use such services? Any others you would suggest?