4tH is a Forth compiler with a little difference. Instead of the standard Forth engine it features a conventional compiler. 4tH is a very small compiler that can create bytecode, C-embeddable bytecode, standalone executables, but also works fine as a scripting language. It supports about 95% of the ANS Forth CORE wordset and features conditional compilation, pipes, files, assertions, forward declarations, enumerations, structures, suspended execution, recursion, include files, etc. It comes with an RPN calculator, line editor, preprocessor, compiler, decompiler, C-source generator, a virtual machine, and a multitasking environment.
amforth is an extendible command interpreter for the Atmel AVR ATmega microcontroller family. It has a turnkey feature for embedded use as well. It does not depend on a host application. The command language is an almost compatible ANS94 forth with extensions. It needs less than 8KB code memory for the base system. It is written in assembly language and forth itself.
FreeForth is a small and fast interactive compiler composed of an extensible set of macros generating inline compact i386 native code, including floating-point instructions, and an easy interface to Linux and Windows dynamic libraries. It uses two stacks to pass subroutines arguments and results separately from return addresses, like other Forth dialects, but unlike them, it is a simpler pure compiler (without an interpreter) offering interactivity through "anonymous" subroutines which are executed by their closing ";" macro. FreeForth is fully documented by 100K of interactive online help. Since its first release in 2006, it has been used every day for cross-development of realtime industrial applications embedded in microcontrollers, and for PC-controlled manufacturing test benches. The FreeForth distribution includes an interactive incremental assembler for the MSP430 microcontroller family.
Gforth is a fast and portable implementation of the ANS Forth language. It works nicely with the Emacs editor, offers some nice features such as input completion and history and a powerful locals facility, and it even has (the beginnings of) a manual. Gforth employs traditional implementation techniques: its inner innerpreter is indirect or direct threaded. Gforth runs under Unix, Win95, OS/2, and DOS and should not be hard to port to other systems supported by GCC.
Factor is a dynamically-typed stack-based programming language. Factor runs on various OSes and CPU architectures, and provides an optimizing compiler, interactive development environment, powerful collections, higher order programming, continuations, and a growing library of contributed code.
bigFORTH is a native code Forth. It was originally developed on the Atari ST for the Motorola 68k processor and was recently ported to Intel 386, running under a DOS extender (GO32). bigFORTH is available for Linux and Windows 95/98/NT in pre-beta-test. This version is available under GPL. The most striking new feature is the graphical user interface MINOS and the form editor Theseus. MINOS is a graphic user interface (GUI) for X, written for bigFORTH-Linux and bigFORTH-Win32. It includes a rapid GUI developement editor (Theseus).
RetroWeb is an extension for RetroForth intended to ease the task of creating Web pages. It is still close to HTML, but offers a more compact syntax. Most importantly, it allows you to work with the full power of Forth to generate HTML code. It can be used to create both static HTML files and simple dynamic CGI responses.