Any simple text analytics tools for chunking survey questions and comments

Hi,  would like to seek all your expertise to recommend a free open source tools that can become clustering on Survey data,   the enterprise tools like SPSS, SAS etc are overkill as our data are less than 1-2K, and what we need to do is chunk all the verbatim questions, comments or forum threads into topics,  sub-categories, categories

I had tried Lexalytics in the past still not what we want for end users (general casual user),    as most of the time we will be inputting our own lexicon and feed to this tools,  so the default taxonomy, lexicon library may not be accurate after the 1st run

best that this tool is on premises (without internet connection)

Thank you all