SWI-Prolog is distributed as platform specific binary package for popular platforms (currently MS-Windows and MacOS X). For Ubuntu Linux we provide a PPA. For all Linux systems supporting snap we provide the snap package swi-prolog.

The source package is configured using CMake. The sources builds on a wide range of 32 and 64 bit systems with an ANSI C compiler. The MS-Windows version is built using MinGW as a cross-compiler under Linux. See the file README.mingw in the toplevel directory.

SWI-Prolog stable releases have an even minor version number (8.0.x, 8.2.x, 8.4.x, ...) and development releases an odd minor version number (8.1.x, 8.3.x, ...). The development versions are released frequently, typically every couple of weeks). A new stable cycle is started when the development version has improved enough to make upgrading valuable for many users and large changes to the development versions have proven to be stable. As of 7.4.x we plan to provide regular stability and security fixes for the stable version and we will avoid incompatible changes.

Note that the version numbers do not follow semantic versioning rules. The major, minor version and development release patch version merely consolidate development cycles. Only the stable patch level is practically guaranteed to maintain backward compatibility.

All sources are available on GitHub. The repository swipl.git is used for the stable versions and the repository swipl-devel.git for the development series. Releases are tagged *V*Major.Minor.Patch.

9.3.x

Current development series.

9.2.x

Adds a Python interface (Janus), new C++ interface, improved tooling (profiling, coverage analysis, unit testing and installing add-ons) and command line apps. Sources are now strict C11 and the full system can be build using Micorsoft VS2022.

9.0.x

Adds support for WASM WebAssembly. Adds sweep, a new GNU-Emacs package with semantic highlighting. Adds a new comprehensive and type-safe C++ interface with SWI-cpp2.h.

8.4.x

Adds interfaces to Redis and STOMP micro services, isolated transactions and additional thread synchronization, new support for deterministic coding using $/0, $/1 and det/1 and monotonic tabling.

8.2.x

Brings advanced tabling support of XSB to SWI-Prolog: Well Founded Semantics, restraints, incremental tabling and shared tabling. It also makes rational numbers primary citizens. Using Google's tcmalloc reduces the memory footprint drastically on some multi-threaded workloads.

8.0.x

Indexing on multiple arguments together, indexing inside compounds, Mode-directed tabling, saved states using ZIP files, many deployment enhancements. Moved build environment to CMake and removed most of the build tool dependencies. Builds documentation along with the binary.

7.6.x

Major release. Multi-argument indexing, better multi-threaded performance, threaded global GC (atoms and clauses), mode-directed tabling, restored same expand and directive semantics for initial load and reloading files, cleaner initialization and command line handling.

7.4.x

Major release. More robust and better scalable support for multi-core hardware, tabling, engines. Many enhancements to the RDF, HTTP and SSL libraries. This is the first release licensed under the Simplified BSD (BSD-2) license.

7.2.x

Major release, providing native key-value support by means of dicts, native strings using "hello world" syntax, web-accessible Prolog engines (Pengines) and a high level SQL library called CQL. See extensions.

6.6.x

Mostly a stability release. 6.6.x comes with some modification, notably to processing commandline arguments. It has been stabilised rather quickly because the 7.1.x branch introduces many and partially incompatible changes.

6.4.x

RDF database version 3, quasi quotations, many enhancements to HTTP and HTML environment, many enhancements to the development tools, bug fixes.

6.2.x

The pack package installer, better :- include(file). support, many enhancements to debugger and environment. Windows version built using MinGW (about 20% faster then MSVC2005 version).

6.0.x

Stable branch created from 5.11.37. Notably provides just-in-time indexing on multiple arguments and supports the PDT Eclipse IDE out of the box.

5.11.x

External requirements have forced the release of 5.10.x before the wishlist of new functionality was complete. Notably generational GC remains on the wishlist.

5.10.x

Stable branch with the achieved 5.9.x enhancements: better scalability in terms of memory usage and concurrency, better reliability and better compatibility.

5.8.x

Stable branch providing performance enhancements from 5.7.x, many extensions and enhancements to the libraries; notably the web and semantic web libraries.

5.6.x

Stable branch providing UNICODE handling, unbounded and rational arithmetic, enhanced Leuven CHR system, clp(q,r), clp(fd), much enhanced (semantic) web libraries, etc.

5.4.x

Stable branch providing attributed variables, coroutining, CHR (Constraint Handling Rules), infinite trees (cyclic terms) and many more. This is the last version that runs on Windows 95/98/ME. 5.5.x and later require Windows NT, 2000 or XP.

5.2.0

Stable version providing multi-threading.

5.x.y

Moved to uniform LGPL license. Standard distribution contains core packages: XPCE (graphics), TCP/IP, CGI, SGML/XML/HTML/RDF, HTTP, ODBC and many more.

3.4.5

Version prior to integration. Compliant to the ISO Prolog standard (part1).

3.2.9

Last pre-ISO version. As 3.3.0 is not fully upward compatible this version will remain on this server for a while. It will not be maintained (by us)