CHICKEN is a Scheme-to-C compiler supporting most of the language features as defined in the Revised^5 Report on Scheme. CHICKEN generates quite portable C code, and files compiled by it (including itself) should work without any changes on most platforms. The whole package is distributed under a BSD license and as such free to use and modify as long as you adhere to its terms (see the manual). Linkage to C modules and C-library functions is straightforward, so it's easy to access C from Scheme. Compiled code can be embedded into existing C programs without problems. The generated code supports full tail-recursion, first-class continuations, multiple values and dynamic-wind.