Tools for working with word frequencies from various corpora.
Author: Rob Speer
wordfreq is freely redistributable under the MIT license. See MIT-LICENSE.txt.
Ngram Viewer graphs and data may be freely used for any purpose, although acknowledgement of Google Books Ngram Viewer as the source, and inclusion of a link to http://books.google.com/ngrams, would be appreciated.
It also contains data from the University of Leeds Centre for Translation Studies (see http://corpus.leeds.ac.uk/list.html), which is freely redistributable under a Creative Commons Attribution license.