An interactive multithreaded Scheme interpreter with turtle graphics for Windows 95, based on SCM.

Newer versions here. Scheme system for the Palm Pilot PDA developed by Fred Bayer.

Ksi is a portable, embeddable Scheme implementation written in C. Unfortunately its documentation is all in Russian at this point.

Based on Mini-Scheme, tiny implementation, almost a full R5RS Scheme. Goal: embedded scripting use, but works as standalone interpreter and extensible shell tool. Recent changes reduced executable size to about 64KB on Linux/x86. [BSD]

Tiny, expressive; made to teach advanced computer science ideas to non-computer science students; mixes power of languages like Scheme, with standard infix notation known from calculus. Has: garbage collected tables (arrays), higher order functions, o...

A distributed implementation of Scheme that permits efficient transmission of higher-order objects such as closures and continuations.

Portable scheme interpreter by Britt Park. Other free software: Cdoc, simple program to generate pretty TeX output from annotated C/C++ code. Userblock, simple user space block device driver kit for Linux. UVFS, user space filesystem kit.

Portable Scheme implementation, conforms to IEEE/ANSI standard, supports all features of R5RS Report, many features of Chez Scheme and various SRFIs. Derived from XScheme: object system dropped, many changes, additions.

A compact (<64 Kb) implementation of R4RS Scheme that compiles for VxWorks/Tornado (and is integrated with the system symbol table). [Open source, Artistic License]

Yet more Scheme implementations from the CMU AI Repository. Many of these are also available from the Indiana University Scheme Repository.