A superset of the Scheme dialect of Lisp with extensions to support object-oriented programming.

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.

Scheme Shell, broad-spectrum system programming environment for Unix, embedded in R5RS Scheme 48. Supports concurrent system programming, sophisticated I/O and automatic garbage collection for process resources.

A fast, small Scheme interpreter which is mostly compliant with the R5RS standard.

Derived from STkn implementation based on an ad-hoc virtual machine, byte compiler; compilable as library to embed in other programs, has object system with MOP, multiple inheritance, generic functions, multimethods, module system, full R5RS tower of ...

Scheme environment for Windows 3.1/95; interpreter independent, though defaults to Jaffer's SCM. Used at University of Lille 1, France, for introductory programming course. Free downloads. English, Francaise.

System with one goal: enable Scheme programming style where C(++) is usually needed; makes Scheme practical via features found in most normal languages but not Scheme and functional programming. Generators for C code, Java Virtual Machine, .NET byteco...

A portable Scheme implementation written by Aubrey Jaffer.

Even more Scheme implementations freely available from the Indiana U. repository.

Statically-typed Scheme, written in Infer, combines many of the best features of Scheme and ML; polymorphic. NSF funded. Description, draft manual.