An extended version of TeX that can create PDF directly from TeX source files and enhance the result of TeX typesetting with the help of PDF. When PDF output is not selected, pdfTeX produces normal DVI output.

A standard of \specials for turning (La)TeX documents in hyperdocuments supported by previewers for DVI and Postscript files.

An extended version of pdfTeX using Lua as an embedded scripting language. Roadmap, FAQs, source code and documentation.

Omega is an extension of TeX developed by John Plaice (Universite Laval, Canada) and Yannis Haralambous (Atelier Fluxus Virus, France) aimed primarily at improving TeX's multilingual abilities.

Free Persian/English bidirectional typesetting system based on TeX. Currently available only for DOS.

Python programming plus TeX typesetting. Information about the concept, documents and links to the SourceForge page with download and mailing list. Also home of Active TeX, a forerunner of PyTeX, and the TeX daemon.

The NTS projected is aimed at developing successor for TeX; a New Typesetting System.

New TeX engine in development, written in Java and based on NTS, -TeX, pdfTeX, and (Omega). Development information, documentation, mailing lists and download.

A modern and free C++ implementation of TeX based on CommonTeX.

Program licensed under the GNU GPL which parses LaTeX math expressions emitting images which can be used directly in HTML documents. Introduction, manual and download.