Stanford Natural Language Processing Group - CoreNLP

set of tools for natural language processing (NLP) tasks such as tokenization, part-of-speech tagging, lemmatization, parsing, named entity recognition, coreference resolution and sentiment analysis.

OpenNLP

OpenNLP is an open source Java library for performing natural language processing tasks. It includes tools for tokenization, part-of-speech tagging, parsing, information extraction, and more.

CoreNLP

Open source library for natural language processing

SpaCy

spaCy is a free, open-source library for Natural Language Processing in Python.