AntConc is free concordance software.
A software tool for performing concordance – the analysis of a set of words within its immediate context - on a body of text. The tool performs full concordance, reading and analysing each and every word in a text. It was initially written for the analysis of English texts, but has since been extended to cater for other Western languages. Limited support is also provided for text in East Asian scripts, such as Chinese and Korean.
"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. This version includes a web-spider which reads as many pages as you want from a particular website and puts them in a TextSTAT-corpus. The new news-reader, too, puts news messages in a TextSTAT-readable corpus file.
TextSTAT reads MS Word and OpenOffice files. No conversion needed, just add the files to your corpus...
The Field Linguist's Toolbox is Windows software for maintaining lexical data, and for parsing and interlinearizing text.
Wmatrix is web-based software for corpus analysis and comparison. It provides a web interface to the USAS and CLAWS corpus annotation tools, and standard corpus linguistic methodologies such as frequency lists and concordances. It also extends the keywords method to key grammatical categories and key semantic domains.
Word and Phrase utilizes the Corpus of Contemporary American English (COCA) to analyze texts for word frequencies, collocations, and concordance lines. Users copy and paste texts into a web interface.