This page will help you obtain Tcl/Tk for your computer. There are many ways to do this; we'll outline the most popular choices.Tcl and Tk are available on a wide variety of platforms, including Windows, Mac, and essentially all flavors of Unix (Linux, Solaris, IRIX, AIX, *BSD*, etc.).
Tcl/Tk is open source (based on a BSD-style license), so you can use it and modify it virtually any way you want, including for commercial uses. Here is the Tcl source distribution license, but be sure to check the license for any particular distribution you use.
Other Software: We also catalog a small set of other related software.
The "Batteries Included" ActiveTcl Distribution
By far the easiest way to get Tcl/Tk installed is via ActiveState's free ActiveTcl distribution, which includes precompiled versions of not only the core Tcl and Tk, but dozens of the most popular extensions, to provide you with a rich set of Tcl development tools with a single software installation. Versions are available for AIX, HP-UX, Linux, Mac OS X, Solaris, and Windows.
The Tcl/Tk Source Code Distributions
You can easily compile your own versions of Tcl and Tk from these source code distributions. Tcl/Tk 8.6 is the current stable version.
Living on the edge? To see what's coming up, you may want to track ongoing development of Tcl and Tk and several packages over at core.tcl.tk. You may also be interested in the previous stable version, Tcl/Tk 8.5.
Already have Tcl/Tk?
Tcl and Tk come preinstalled on most Unix systems, as well as on Mac OS X, so it may well be worth a quick look.
However, if it is there, you'll want to check if you've got a recent version. To check, start Tcl/Tk (usually via running "tclsh" or "wish" from a command line), and typing "info patchlevel". This will tell you what version you're running.