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 interpreter is
indirect or direct threaded.

Homepage:
https://www.complang.tuwien.ac.at/forth/gforth/
