Clozure Associates

ccl macl mcl openmcl ccl

Clozure CL

Clozure Associates develops, hosts, and maintains Clozure CL (CCL), a complete open source implementation of the Common Lisp standard.


  • Linux

  • OS X

  • Windows


  • x86

  • ARM

  • PowerPC


  • Fully compiled code.

  • Fast, precise, compacting, generational garbage collection.

  • Native OS threads on all platforms.

  • A complete mature foreign function interface.

  • Full support for SLIME, ASDF, and QuickLisp.

  • A native IDE on OS X with Objective C and Cocoa integration.

Clozure CL is available for download from

For Clozure CL support or to enquire about custom extensions to Clozure CL, please e-mail

What's in a Name?

1984: Coral Sofware begins development of a Common Lisp for the Macintosh, called Coral Common Lisp (CCL).

1987: Coral Common Lisp 1.0 released.

1987: CCL renamed Macintosh Allegro Common Lisp (MACL) as part of a joint marketing effort with Franz Inc.

1988: Apple Computer purchases Coral Software. CCL renamed Macintosh Common Lisp (MCL).

1994: Digitool takes over sales, support, and development of MCL.

1998: Gary Byers forks the sources and begins porting the non-GUI portions of MCL to Linux while working for JPL.

2001: This fork released as free open source software under the name OpenMCL.

2007: OpenMCL renamed Clozure Common Lisp (CCL).