There are many commercial implementations of TeX. The first appeared not long after TeX itself appeared.
What follows is probably an incomplete list. Naturally, no warranty or fitness for purpose is implied by the inclusion of any vendor in this list. The source of the information is given to provide some clues to its currency.
In general, a commercial implementation will come “complete”, that is, with suitable previewers and printer drivers. They normally also have extensive documentation (i.e., not just the TeXbook!) and some sort of support service. In some cases this is a toll free number (probably applicable only within the USA and or Canada), but others also have email, and normal telephone and fax support.
PC; TrueTeX Runs on all versions of Windows.
Richard J. Kinch
7890 Pebble Beach Court
Lake Worth FL 33467
pcTeX Long-established: pcTeX32 is a Windows implementation.
Personal TeX Inc
725 Greenwich Street, Suite 210
San Francisco, CA 94133
PC; Scientific Word Scientific Word and Scientific Workplace
offer a mechanism for near-WYSIWYG input of LaTeX documents; they
ship with TrueTeX from Kinch (see above). Queries within the UK
and Ireland should be addressed to Scientific Word Ltd., others should be
addressed directly to the publisher, MacKichan Software Inc.
Dr Christopher Mabb
Scientific Word Ltd.
130B Main Street
MacKichan Software Inc.
19307 8th Avenue, Suite C
Poulsbo WA 98370-7370
AmigaTeX A full implementation for the Commodore Amiga,
including full, on-screen and printing support for all PostScript
graphics and fonts, IFF raster graphics, automatic font generation,
and all of the standard macros and utilities.
Radical Eye Software
PO Box 2081
Stanford, CA 94309
Source: Mail from Tom Rokicki, November 1994
Note that the company Y&Y has gone out of business, and Y&Y TeX (and support for it) is therefore no longer available. Users of Y&Y systems may care to use the self-help mailing list that was established in 2003; the remaining usable content of Y&Y’s web site is available at https://www.tug.org/yandy/
FAQ ID: Q-commercial