Rep 5 is a suite of tools supporting research into, and applications of, a range of conceptual representation techniques using conversational constructivist methodologies based on George Kelly's (1955) Personal Construct Psychology (PCP)—see also the International Handbook of Personal Construct Psychology (Fransella, 2003). In its various versions, it aims to provide personal, professional and research support for promoting understanding of individual and communal psychological and social processes. It provides conversational tools for constructing and analyzing grids (RepGrid), and nets (RepNet). Grids are a generalization of Kelly's conceptual grids for eliciting construct networks through examples of their application, and nets are a generalization of visual syntactic structures used for representing construct networks directly in visual languages. It supports the use of grid and net tools separately and in combination, including integration between those tools and other applications such as word processors, spread sheets and knowledge representation and inference systems.

There are three versions of Rep 5: the Personal version which supports elicitation and simple analysis of grids with up to 15 elements and 15 constructs; the Research version which supports grids of any size, full analyses of single and multiple grids, and access to an integrated RepServe web server providing WebGrid access on the same computer; and the Enterprise version which supports categorical and numeric data in grids and a RepServe web server accessible through intranets or the Internet supporting remote data collection. RepNet is supported in all versions, and RepServe in the Research and Enterprise versions.

Some major new features in Rep 5 are:-
1 The RepServe web server is now an integral component of Rep 5 enabling WebGrid functionality to be offered on the local machine in the Research version and across the Internet in the Enterprise version. In particular, this supports grid elicitation through web clients taking full advantage of the widespread experience of using web browsers, their multimedia capabilities, and their support for remote data collection across the web. The grid files saved from web elicitation are compatible with all the Rep 5 editing and analysis tools. The web server is scriptable in the RepScript programming language, and users can modify the supplied WebGrid scripts, translating them into other languages and customizing them for their own purposes.
2 The RepScript scripting language used in previous versions to support interactive grid elicitation has been standardized and documented to provide an open-architecture application program interface (API) to Rep 5 functionality for grid and net elicitation and analysis.
3 Three-dimensional plotting capabilities have been added for the graphic output of the PrinGrid principal components analysis and the CrossPlot presentation tool.
4 The capability has been added to collect additional data items and store them in grid files.
5 In the Enterprise version additional data types are supported in grids, including labeled categories, integers and numbers providing richer capabilities for knowledge representation, modeling and management.
6 The RepNet visual language component has been substantially enhanced with additional link types, the ability to represent a node's state with visual markers, and a scripting language enabling interaction with nets of nodes and links to be programmed. A sample script supporting 'expert system' inference through deductive and abductive reasoning modeling anticipatory processes in construct net conceptual models is provided.