etcML (Easy Text Classification with Machine Learning) is a free text analysis tool from Stanford University that uses machine learning to identify positive and negative sentiments in texts. Users can analyze their own dataset, use a dataset provided with the tool, or search Twitter for keywords of interest.
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This tool, according to the creator's statement (https://web.archive.org/web/20141224174307/http://etcml.com/), is discontinued sincde June 19, 2014.