ACL2 - Applicative Common Lisp, multipurpose system. Most common uses: language for programming, specification, modeling; a formal mathematical logic, semi-automatic theorem prover. [Open Source, GPL]
Allegro CL - Franz Allegro is a CL compiler available for Linux, Unix, and Windows. Free and commercial versions.
Armed Bear Common Lisp - ANSI CL, runs on Java Virtual Machine, JVM. Has runtime system, compiler turns Lisp source to JVM bytecode, interactive REPL to develop programs. [Open Source, GPL]
CLISP - Interpreter and FASL compiler, portable ANSI Common Lisp implementation, CLtL2 conformant, available for many platforms; multilingual user interface. [Open Source, GPL]
CMU Common Lisp: CMUCL - CL implementation, runs on most major Unix platforms, mainly conforms to ANSI CL standard; fast compiler outputs native code, of near C speed; powerful module system, data structures. [Freeware]
Common Lisp Hypermedia Server: CL-HTTP - World Wide Web server implemented in CL; goal: to rapidly prototype, smoothly evolve experimental, novel, or complex applications for the WWW. [Open Source]
Common Lisp to C Compiler: CLiCC - Not a CL system, compiles Lisp programs into working C programs; is coded in Lisp; supports strict, very large subset of CL + CLOS. Descriptions, documents, downloads. [Open Source, GPL]
Corman Technologies - Corman Lisp and PowerLisp compilers with support for 68k and PPC Macs. [Shareware/Freeware for personal use]
Digitool, Inc. - Makes Macintosh Common Lisp, MCL: for 68k, PowerPC; compiles to native code, supports threads, integrates well into Mac OS, fun; Common Lisp Interface Manager, CLIM: platform independent user interface system, to target other Lisp platforms.
DotLisp - Interactive Lisp dialect for CLR (.Net) scripting, development. Deep CLR integration, sharing type system, GC, other runtime services, transparent access to .Net w/o a FFI or wrappers. Open source, BSD.
ECL: Embeddable Common Lisp - ANSI CL, has interpreter, Lisp to C compiler, can make standalone executables or libraries to call from C programs. [Open source, LGPL]
ECoLisp: ECL - Embeddable Common Lisp, implementation to embed in C-based programs; FTP site.
EuLisp - Dialect of scope similar to Common Lisp, object-oriented, but organized differently, with claimed cleaner design, by a group of European industrial and academic Lisp users and implementors. Description, FTP server, contacts, links.
GOO - Generic Object Orientator, replaces Protojunior: OO, type-based prefix-syntax language; like a simpler, more dynamic, Lispy Dylan and OO Scheme; simple, efficient, extensible. Description, manual, rationale, downloads.
Hedgehog Lisp - Small dialect for low-end and embedded devices. Has compiler to bytecode and corresponding interpreter, coded in standard C, efficient, portable, can be compiled to very small executable or library. [Open Source, GPL]
librep - Shared library implementing Lisp dialect that is lightweight, fairly fast, highly extensible. Has interpreter, byte-code compiler, virtual machine. Programs may use interpreter as an extension language, or it may be used for standalone scripts. [Open source, GPL]
LispWorks Ltd. - Was Xanalys. Makes LispWorks ORB, Liquid Common Lisp, KnowledgeWorks; integrated cross-platform development tool, full native ANSI Common Lisp for Linux, Mac OS X, Unix, Windows; related products, services. Free and commercial versions.
Lush: Lisp Universal SHell - Object-oriented language for researchers, experimenters, engineers, for large-scale numerics and graphics. Merges 3 languages: (1) weakly-typed, garbage-collected, dynamically scoped, interpreted language with Lisp syntax, (2) strongly-typed, lexically-scoped compiled language with Lisp syntax, (3) C language, can be freely mixed with Lush code in one program, even in one function.
newLISP - General purpose scripting Lisp dialect for Cygwin, FreeBSD, Linux, Mac OS X, Solaris, Win32; like Scheme but with dynamic scoping; GUI version has IDE with editors and source level debugger, Tcl/Tk frontend. [Open Source, GPL]
OpenLisp by Eligis - ISLisp interpreter, coded in C, ported to over 90 architectures, 16- to 64-bits. [commercial, free non-commercial use]
OpenMCL - An open-sourced Common Lisp implementation for LinuxPPC.
Opus - A version of Berkeley Franz Lisp for 386-based NetBSD systems.
PLisp - Language gets overall syntax from Common Lisp and operators and datatypes from PostScript (PS). Compiler translates PLisp to PS, which can then run on any PS engine. Wiki page with description, links, code samples.
pLISP - Experimental implementation of parallel functional programming. Built as a hybrid architecture, uses simple Lisp interpreter to drive the compiler, and wraps calls to the Graph-reduction VM.
ProLisp - An interpreter for a lexically scoped minimalistic Lisp of Lisp 1.5 type. It written in C++ and currently runs under Linux. [Open source]
PyLisp - Tiny Lisp in Python: brief description, download.
SBCL: Steel Bank Common Lisp - Compiler and runtime system for ANSI CL. Has interactive environment including an integrated native compiler, debugger, many extensions; runs on many platforms. [Open Source, GPL]
Star Sapphire Common Lisp - DOS CL implementation with CLOS. Download, full CL reference manual. From Sapiens Software Corp. [free copyrighted unsupported shareware]
Ufasoft Lisp - Common Lisp development system. Includes command-line and IDE interpreters. Possibility of creating EXE-files. [Free non-commercial and education use]
Wade's Common Lisp: WCL - Implements CL for Linux on x86 hardware, has large CL subset as a shared library that can link with Lisp and C code to make efficient, small programs; suitable for embedding in other programs.