You can go for PatCount (a short form for pattern counting). You can use it for frequency counting of lexical, syntactic, and discoursal features in any text. It is free, light, and has powerful statistical capabilities.
Alternatively, you can use QUITA, which, besidea countIng the number of tokens, calculates a lot of stylometric indexes. Feel free to look here: http://m.miroslavkubat.webnode.cz/software/.