Steel Bank Common Lisp (SBCL) is a high performance Common Lisp
compiler. It is open source / free software, with a permissive license. In
addition to the compiler and runtime system for ANSI Common Lisp, it provides
an interactive environment including a debugger, a statistical profiler, a
code coverage tool, and many other extensions.
SBCL runs on a number of POSIX platforms, and experimentally on Windows. See the download page for supported platforms, and getting started guide for additional help.
The most recent version is SBCL 1.2.11, released April 27, 2015 (release notes).
SBCL's manual is available on the web in html and pdf formats. See the
doc/manual directory in the source code for the current version in TeXInfo source.
Bugs can either be reported directly to SBCL's bug database on Launchpad, or by sending email to the sbcl-bugs mailing list -- no subscription required.