Beautiful Soup

A Python library for extracting data from HTML and XML files.

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.

Natural Language Toolkit (NLTK)

NLTK is a powerful Python library for natural language processing. It includes modules for tokenizing, tagging, parsing, and semantic reasoning, among other useful features.