NLP Common open source/free tools
(reproduced from the Water Wood Community NLP Edition)
*computational Linguistics Toolbox
CLT http://complingone.georgetown.edu/~linguist/compling.html
GATE http://gate.ac.uk/
Natural Language Toolkit (NLTK) http://nltk.org
Mallet Http://mallet.cs.umass.edu/index.php/Main_Page
*english Stemmer
Snowball http://snowball.tartarus.org/
*english POS Tagger
Stanford POS Tagger http://nlp.stanford.edu/software/tagger.shtml
Treetagger http://www.ims.uni-stuttgart.de/projekte/corplex/TreeTagger/
*english Parser
Stanford Parser http://nlp.stanford.edu/software/lex-parser.shtml
Berkeley Parser http://nlp.cs.berkeley.edu/Main.html#Parsing
*english Keyphrase Extractor
KEA http://www.nzdl.org/Kea/index_old.html
*english Name Entity recognizer
Stanford NER http://nlp.stanford.edu/software/CRF-NER.shtml
*chinese Word Segmentator
CAS Ictclas http://www.nlp.org.cn/project/project.php?proj_id=6
Stanford Word segmenterhttp://nlp.stanford.edu/software/segmenter.shtml
*topic Modeling Tools
Matlab http://psiexp.ss.uci.edu/research/programs_data/toolbox.htm
*machine Learning Methods
crf++ http://crfpp.sourceforge.net/
LIBSVM http://www.csie.ntu.edu.tw/~cjlin/libsvm/
*search Engines
Lucene http://lucene.apache.org/
CAS Firtex http://www.firtex.org/
*data Mining Toolbox
Weka http://www.cs.waikato.ac.nz/ml/weka/
From:http://www.thuir.cn/cms/index.php?page=nlp