NLP free tool: NLTK (Natural Language Toolkit)

NLTK (Natural Language Toolkit): open source software to handle human language data.

Developed by Steven Bird and Edward Loper in 2001, it has come a long way. It provides a “suite of text processing libraries for classification, tokenization, stemming, tagging, parsing, and semantic reasoning”.

Here are examples of how to use the NLTK modules: https://www.nltk.org/howto.html

Here are some interactive online demos, including sentiment analysis, tokenization, stemming, tagging and chunking: http://text-processing.com/demo/

Steven Bird, Ewan Klein, and Edward Loper wrote a very comprehensive book, Natural Language Processing with Python, and made it fully available, for free, here: https://www.nltk.org/book/

Please contribute to this cause if you can! https://github.com/nltk/nltk/blob/develop/CONTRIBUTING.md

Their website: http://www.nltk.org/