About Clozure CL

Clozure CL (often called CCL for short) is a free Common Lisp implementation with a long history. Some distinguishing features of the implementation include fast compilation speed, native threads, a precise, generational, compacting garbage collector, and a convenient foreign-function interface.

Starting with version 1.11, Clozure CL is distributed under the terms of the Apache License, version 2.0.

Getting Clozure CL

Clozure CL is available for the following platforms:

See the download page to learn how to download and install Clozure CL.


The documentation page has links to pre-formatted versions of the manaul.

The Clozure CL wiki often contains information that hasn't yet made it into the manual.

Documentation for CCL is written in a notation called CCLDoc. Please see http://trac.clozure.com/ccldoc/ for information about this format and for the source code of the manual.


Mailing lists

The mailing list openmcl-devel@clozure.com is for general and technical discussion of Clozure CL. Note that you must be a subscriber in order to post.


Everyone interested in Clozure CL is welcome to participate in #ccl on irc.freenode.net. The channel logs are available. We also keep logs for #lisp and logs for #scheme.

Reporting bugs

To report a bug or request a feature, please open an issue on GitHub.

Paid support

Fee-based support for Clozure CL is available from Clozure Associates on a per-incident or contract basis. Please send mail to business@clozure.com for more information.