Graphviz is a free, open source graph visualization tool in constant development since 1988. It represents structural information as diagrams of abstract graphs and networks.

CLAWS (Constituent Likelihood Automatic Word-tagging System) is a free parts-of-speech tagging tool from Lancaster University. It has been continuously developed since the 1980s, has consistently achieved 96-97% accuracy, and has been applied to the over 100 million word British National Corpus. This tool is available for download in addition to an on-line 'trial' version.

Tesseract is a free raw OCR engine originally developed by HP Labs and now maintained by Google. It works with the Leptonica Image Processing Library, and is capable of reading a variety of image formats. It can convert images to text in over 40 languages.

TACT (Text Analysis Computing Tools) is a historically important text analysis and retrieval system that was developed from 1986 to 1989 at the University of Toronto in cooperation with IBM and remained in use into the 1990s. It was designed to run in MS-DOS and permitted inquiries on text databases in a number of European languages. Originally available on two 1.44MB floppy disks, the full fileset is now available for free download.

PC-KIMMO is a tool for morphological parsing available since 1985. It is designed to generate and/or parse words, for use by computational linguists, descriptive linguists and others interested in natural language processing. Though this tool is no longer being actively developed, it is still available for download, as is its documentation.

Micro-OCP (Oxford Concordance Program) was a major and historically important textual analysis tool for microprocessor computers. It enabled users to generate concordances, word lists and indexes, in addition to facilitating text markup in COCOA or other markup languages. Micro-OCP was written in FORTRAN, ran primarily in a DOS environment and could be ported to other operating systems including UNIX.

FINNMORF was a tool for generating full lexical paradigms for Finnish words. It modelled Finnish morphological competence, to facilitate identification of the most likely forms of a word within its context. Although the program could not select the correct form from context, the complexity of Finnish required sophisticated modelling to correctly determine the possible root form of a given word. As such, FINNMORF represented a significant contribution to computational linguistics.

WordCruncher is long-standing text indexing, retrieval and analysis program offered by Brigham Young University. Its functions include tagging, contextual searching, collocation and analytical reporting, and its development has been active since the 1980s.

DV-COLL (Donne Variorum Textual Collation Program) is a historically important textual collation program first introduced in the 1980s and maintained into the present. It was originally designed to assist in creating a digitized corpus of the works of John Donne, and has been opened to other researchers for collecting, comparing and analyzing the works of other poets.

FRANTEXT is a historically and culturally important database of French literary, philosophical and technical texts with an emphasis on diversity and representation, spanning the Middle Ages to the present, and offered on a subscription basis. This resource is aimed at linguists and literary scholars in the humanities and social sciences, and is notable for its inclusion of a powerful search engine called Stella. Stella is a sophisticated NLP search suite, and includes regular expression search, lemmatization, vocabulary list and entity categorization functions.