Chibi-Scheme
Chibi-Scheme is a very small library with no external dependencies, intended for use as an extension and scripting language in C programs. In addition to support for lightweight VM-based threads, each VM itself runs in an isolated heap allowing multiple VMs to run simultaneously in different OS threads. The default language is the R7RS (scheme base) library, with support for all libraries from the small language.
Chibi-Scheme is an implementation of Scheme.
Other implementations of Scheme.