Gambit-C includes a Scheme interpreter and a Scheme compiler which can be used to build standalone executables. Because the compiler generates portable C code it is fairly easy to port to any platform with a decent C compiler. The thread system is very efficient and can support millions of concurrent processes.
The Gambit-C system conforms to the R4RS, R5RS and IEEE Scheme standards. The full numeric tower is implemented, including: infinite precision integers (bignums), rationals, inexact reals (floating point numbers), and complex numbers.