Why use TextRazor and pay for it ?
Why use TextRazor and pay for it ?
Also we found the Stanford tools (and the other open source NLP tools) were difficult to integrate into "production" apps for various reasons. One big one was performance - we aim to run the full parsing and extraction pipeline on an average news story in a few hundred milliseconds, which can be an order of magnitude faster than the others.
Edit: To be specific, it looks very similar. What do you have that Calais doesn't?
One thing that Open Calais does that I really like is that they attempt to have a single URI uniquely identifying recognized named entities. This is useful because, for example, when it recognizes President Bill Clinton, you get a reference to a unique URI, even if his name, title is different in different processed texts.
Thomson-Reuters bought ClearForest several years ago, thus acquiring Calais. If you are interested in text mining, and if you haven't experimented with Open Calais, then please put that on your TODO list.