Steel Bank Common Lisp - Steel Bank Common Lisp (SBCL) is a high performance Common Lisp compiler.
CLISP - CLISP is a portable ANSI Common Lisp implementation and development environment by Bruno Haible.
CMU Common Lisp - CMUCL is a high-performance, free Common Lisp implementation.
Guile - Guile is the GNU Ubiquitous Intelligent Language for Extensions, the official extension language for the GNU operating system.
Armed Bear Common Lisp - Armed Bear Common Lisp (ABCL) is a full implementation of the Common Lisp language featuring both...
Clozure Common Lisp - Clozure CL (often called CCL for short) is a free Common Lisp implementation with a long history.