Full disclosure, brat author. We were inspired by things like "What's Wrong
With My NLP?" [1] and TikZ-dependency [2]. But, truth be told, there is not
all that many great visualisation tools out there for NLP data. The same goes
for good and freely available NLP toolkits, things like SpaCy is very much an
exception rather than the rule.
[1]: https://code.google.com/p/whatswrong/
[2]: http://sourceforge.net/projects/tikz-dependency/