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.
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.
The Portable Forth Environment implements the ANSI Standard of the Forth programming language. It is fully written in C, and with gcc the virtual machine can be put into cpu registers. The newer development versions implement a set of modern features including modularization and multithreading. The terminal connection itself can be configured to work in an embedded environment.
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.