WordSmith Tools is described as 'integrated suite of programs for looking at how words behave in texts. You will be able to use the tools to find out how words are used in your own texts, or those of others'. There are three alternatives to WordSmith Tools for Linux, Mac and Windows. The best alternative is TextSTAT, which is free. Other great apps like WordSmith Tools are Yoshikoder (Free) and Antconc (Free).
TextSTAT is a simple programme for the analysis of texts. It reads plain text files (in different encodings) and HTML files (directly from the internet) and it produces word frequency lists and concordances from these files.
AntConc is a freeware, multiplatform tool for carrying out corpus linguistics research and data-driven learning. It runs on any computer running Microsoft Windows (tested on Win 98/Me/2000/NT, XP, Vista, Win 7)