The Versioning Machine, now in version 4.0, is a framework and an interface for displaying multiple versions of text, and encodes the text according to TEI guidelines. It incorporates features found in both critical editions and electronic publication, in addition to providing an environment for textual editors to comparatively view the results of their edits. This tool may be downloaded for use on a local machine, or hosted on one's server for web usage.

GATE (General Architecture for Text Engineering) is free, open source software offered by the University of Sheffield since 1995. It provides a framework for users to gather a corpus, apply an ontology to it, develop markup, automate the application of the markup to the corpus and add tools such as knowledge facet search, ontology browsing or graphing.

Tesla is a virtual research environment for text engineering - a framework you can use to create experiments in corpus linguistics, and to develop new algorithms for natural language processing. Tesla is a client-server application, which can be used by individual researchers as well as by workgroups. The screenshot below shows the experiment editor of Tesla's Client application.