Hyacinth Prolog
- Prolog WAM-based implementation previously known as Babol Prolog. Still under construction and offered free for non-commercial use.
- http://tomasz.budzen.pl/hyacinth/

K-Prolog
- This is the English download site for this Japanese implementation of Prolog for Solaris, HP-UX, Digital UNIX, Linux and 32-bit Windows environments.
- http://www.kprolog.com/index_e.html

SICStus Prolog 3
- This ISO-conformant, performance-oriented Prolog development system also features interfaces with C/C++, Java and ODBC-compliant DBMS's and an OOP extension.
- http://www.sics.se/isl/sicstuswww/site/

Aquarius Prolog 1.0
- The compiler for this open-source version developed at UCB is built around the Berkeley Abstract Machine, a finer-grained rendition of WAM. An interpreter provided for program development is written in Prolog.
- http://www.info.ucl.ac.be/~pvr/aquarius.html

GNU Prolog
- This compiler accepts Prolog + constraint programs and produces native binaries. The obtained executable is subsequently stand-alone. The size of this executable can be quite small since GNU Prolog can avoid linking the code of most unused built-in predic
- http://www.gprolog.org

ProFIT
- Prolog with Features Inheritance, and Templates: Prolog extension with sorted feature structures (including multi-dimensional inheritance), finite domains, feature search, cyclic terms, templates.
- http://www.coli.uni-saarland.de/publikationen/softcopies/Erbach:1995:EUFa.pdf

Arity/Prolog32
- With a compiler and interpreter written in Prolog, C and assembly language and representing a superset of Edinburgh Prolog, a programming environment is offered for Windows/NT.
- http://www.arity.com/?Tab=products&tab2=prolog

Brain Aid Prolog
- Based on Edinburgh Prolog and extended with object-oriented mechanisms, this Berkeley-style open-source system has a compiler written in Prolog and generates Transputer assembly code.
- http://www.fraber.de/bap/

B-Prolog
- Versatile and efficient CLP system based on Prolog with extensions for programming concurrency, constraints and interactive graphics. Runs on: Windows 9x/NT/2000/XP, Linux, Mac, Solaris, HP-UX, FreeBSD, SonyNews, Aix. Free evaluation version is available.
- http://www.probp.com/

CMU Free/Shareware Prolog
- CMU's AI repository offers a collection of Prolog implementations.
- http://www.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/prolog/impl/prolog/0.html

CU-Prolog
- Constraint Unification Prolog (CUP) developed by the Institute for New Generation Computer Technology (ICOT), Japan. Originally written in C under Unix, MacCup is for Macintosh, DJCup for MS-DOS, with both implementations released as free software.
- ftp://ftp.icot.or.jp/pub/cuprolog/

Qu-Prolog
- The Software Verification Research Centre (Univ. of Queensland) extended version of Prolog currently released under Linux and Solaris is designed primarily as a prototyping language and tactic language for theorem provers, including support for efficient
- http://www.itee.uq.edu.au/~pjr/HomePages/QuPrologHome.html

INRIA wamcc
- Predecessor to GNU Prolog. Compiles Prolog via GCC 2.x
- ftp://ftp.inria.fr/INRIA/Projects/contraintes/wamcc/

EZY Prolog
- A typed prolog interpreter, compatible with Visual Prolog, powrefull syntax checker with flow pattern analyser, GUI designer for declarative GUI, built-in functionality for ODBC, Winsock, regular expressions, text parsing, XML processing, HTML formatted o
- http://www.ezy-software.com/ezyprolog/Prolog_Inference_Engine/ezy_prolog_overview.htm

The YAP Prolog System
- The University of Porto's Edinburgh-style, WAM-based Prolog engine is available on 32-bit machines running Sun and Linux and 64-bit Alphas running OSF UNIX and Linux. An open-source policy is being implemented with regard to distribution.
- http://www.ncc.up.pt/~vsc/Yap/

Visual Prolog
- A full-featured programming environment is offered with all the facilities necessary to write mission-critical, commercial-grade applications. A freeware version is available.
- http://www.visual-prolog.com/

Logtalk
- An object-oriented extension to the Prolog programming language. It integrates logic programming with object-oriented and event-driven programming. Compatible with most Prolog compilers. [Open source]
- http://www.logtalk.org/

Trinc-Prolog, an object oriented prolog for Windows
- Trinc-Prolog is a new development tool for the prolog language. Trinc-Prolog supports the ISO Prolog standard and has extended the prolog language with innovative object oriented features. TPWIN,an OO class library is available to develop Windows applicat
- http://www.trinc-prolog.com/

Reform Prolog
- Recursion-parallel Single Program, Multiple Data (SPMD) implementation; assumes one sequential worker and arbitrary, fixed number parallel workers, each worker is process, can have more workers than processors. Successor: High Performance Erlang. [Open So
- http://user.it.uu.se/~thomasl/reform.html

Strawberry Prolog
- This Prolog compiler for Windows 95/98/NT and Unix/Linux supports OLE and Prolog CGI Scripts. Strawberry Prolog is suitable for client-server applications and has unique debugging facilities.
- http://www.dobrev.com/

Quintus Prolog
- The Swedish Institute for Computer Science's implementation of Prolog for UNIX and PC platforms is embeddable, integrable and commercial-strength.
- http://www.sics.se/isl/quintus/

IF/Prolog
- A Prolog implementation for use in industrial and commercial environments. It complies with the ISO Prolog standard and runs on UNIX and MS-Windows environments. IF/Prolog has a rich set of interfaces to standard software components and an additional Cons
- http://www.ifcomputer.de/Products/Prolog/

NU-Prolog
- The successor of MU-Prolog, this compiled Prolog system designed and implemented in the mid-80's as a 'purer' logic solution, interfaces with UNIFY databases and is available under an academic license.
- http://www.cs.mu.oz.au/~lee/src/nuprolog/

Ciao Prolog Development System
- Full ISO-Prolog compliant system, modular design allows language restriction and extension. Descriptions, contacts, mail lists, downloads. [Open Source, GPL]
- http://clip.dia.fi.upm.es/Software/Ciao/

BinProlog
- BinNet Corporation offers a high-performance, robust Prolog system able to generate C/C++ code and standalone executables and providing high-level networking along with secure internet programming integrated with rule-based reasoning components.
- http://www.binnetcorp.com/BinProlog/

Logic Programming Associates
- WIN-PROLOG, DOS-PROLOG, MacProlog32 compilers. Products range from Prolog++ an OOPs extension, flex an expert system toolkit, and various web based technologies. [Commercial]
- http://www.lpa.co.uk/ind_pro.htm

Amzi! Prolog + Logic Server
- This extensible Prolog version runs under Windows, Linux, Solaris and HP/UX, supporting development of client and server applications embeddable in the web, C/C++, Java, Delphi, Visual Basic and other environments. An IDE is available for Windows along w
- http://www.amzi.com/