Retro is a modern, pragmatic Forth drawing influence from many sources. It is clean, elegant, tiny, easy to grasp, and adaptable to many tasks.

It's not a traditional Forth. Drawing influence from colorForth, it uses prefixes to guide the compiler. From Joy and Factor, it uses quotations (anonymous, nestable functions) and combinators (functions that operate on functions) for much of the stack and flow control. It also adds vocabularies for working with strings, arrays, and other data types. Source files are written in Unu, allowing for simple, literate sources.

The source and documentation are distributed under the ISC license.


RetroForth 2024.1 (source, documentation, and examples) & Release Notes


Latest Snapshot

retro.c (amalgamation, for BSD, Linux, macOS, Haiku, and Windows)




Updated from the development snapshots.


Browse Examples


Development is supported by a wonderful set of patrons over on patreon.

My thanks to Kiyoshi Yoneda, Lobo, yoyofreeman, Dave S, Octavio Turra, oneearedrabbit, Tobias Amman, Nuno, Eli, Brad S, Bartels Jon Randy, Scott McCallum, Rick, and BurnedOut for their generous support over the last few years.

If you are interested in a related, but smaller system, take a look at Konilo.