Software

AgenaRisk
Bayesian network, simulation and risk analysis software. Supports exact and approximate inference in hybrid and dynamic networks for decision support, diagnosis, statistical learning and prediction applications.
http://www.agenarisk.com

BayesBuilder
A tool for constructing and testing Bayesian networks.
http://www.snn.ru.nl/nijmegen/index.php3?page=31

BayesiaLab
Bayesian network laboratory producing a broad set of tools for structure learning, analysis, adaptive questionnaires, and dynamic Bayesian networks
http://www.bayesia.com

Bayesian Knowledge Discoverer
Able to learn Bayesian Belief Networks from (possibly incomplete) databases. Algorithm based on the Bound and Collapse estimation method.
http://www.bayesware.com/

Bayesian Network Toolbox (BNT)
Kevin Murphy's MATLAB toolbox - supports dynamic BNs, decision networks, many exact and approximate inference algorithms, parameter estimation, and structure learning
http://www.ai.mit.edu/~murphyk/Software/BNT/bnt.html

Bayesian Network tools in Java (BNJ)
Open-source suite of software tools for research and development using graphical models of probability, published by Kansas State University Laboratory for Knowledge Discovery in Databases (KDD)
http://bnj.sourceforge.net

Bayesline
Very generic and free (LGPL) Belief Network Framework in C++ - supports a broad range of knowledge and dependency types for network variables and clusters of variables
http://bayesline.sourceforge.net

Belief Net Power Constructor
System based on Jie Cheng's three-phase belief network construction algorithm. Includes a wizard-like user interface and a belief network construction engine.
http://www.cs.ualberta.ca/~jcheng/bnpc.htm

BNet Desktop Software and Developer Toolkits
BNet.Builder is a belief network software application. BNet.EngineKit provides an embeddable engine.
http://www.cra.com/bnet

BUGS - Bayesian inference Using Gibbs Sampling
Bayesian analysis of complex statistical models using Markov chain Monte Carlo (MCMC) methods.
http://www.mrc-bsu.cam.ac.uk/bugs/

Charles River Analytics, Inc.
BNet™.Builder is a desktop application for rapidly creating Belief Networks, entering information, and getting results. BNet.EngineKit is a developer toolkit for researchers and engineers to use to embed belief networks in software applications.
http://www.cra.com/commercial-products-services/belief-network-modeling.asp

CleverSet, Inc.
Develops and exploits proprietary Relational Bayesian Modeling (RBM) technology and applications that provide real-time, actionable results from large amounts of dynamic, multi-faceted, ambiguous information.
http://www.cleverset.com

Complex Systems Computation Group (CoSCo)
BAYDA software implements Bayesian predictive discriminant analysis, where the aim is to build a model for predicting the value of one discrete (class, group, category) variable using other variables.
http://cosco.hiit.fi

DecsionQ Bayesian Predictive Analysis Software
A data mining software company that has a fully automated data modeling and predictive analytics package.
http://www.decisionq.com

Genie/Smile
GeNIe is a development environment for building graphical decision-theoretic models running under Windows operating systems. SMILE is its portable inference engine, consisting of a library of C++ classes, currently compiled for Windows, Solaris and Linux.
http://www2.sis.pitt.edu/~genie/

HUGIN EXPERT - Hugin
Developers of the Hugin tool
http://www.hugin.com/

Intel's Open Source Networks Library
PNL is a full function, free, open source, graphical models library released under a BSD style license.
http://www.intel.com/technology/computing/pnl/

JavaBayes
Bayesian networks in Java.
http://www.cs.cmu.edu/~javabayes/Home/

Knowledge Industries, Inc.
Builds and licenses diagnostic software based upon Bayesian Belief Networks for medical, industrial and management applications. Software includes editors/compilers, test/review tools and inference engines embeddable in stand-alone and web-based applications.
http://www.kic.com

Lumina Decision Systems
Makers of Analytica, visual software tool for creating, analyzing, and communicating quantitative business models.
http://www.lumina.com/

Microsoft Belief Network Tools
Free Windows software for creation, assessment and evaluation of belief networks.
http://www.research.microsoft.com/dtas/msbn/default.htm

MIM
Windows program for graphical modelling.
http://www.hypergraph.dk/

Norsys Software Corp.
Netica is a complete program for working with belief networks and influence diagrams. Feature compiles belief (Bayesian) networks into a junction tree of cliques for fast probabilistic reasoning.
http://www.norsys.com/netica.html

Pulcinella
Tool for propagating uncertainty through local computations based on the general framework of valuation systems proposed by Shenoy and Shafer.
http://iridia.ulb.ac.be/pulcinella/Welcome.html

RISO
Robert Dodier's open source package for distributed, heterogeneous belief networks in Java - allows different conditional distributions
http://riso.sourceforge.net

SamIam: Sensitivity Analysis, Modeling, Inference and More
A tool for modeling and reasoning with Bayesian networks, developed in Java by the Automated Reasoning Group of Professor Adnan Darwiche at UCLA.
http://reasoning.cs.ucla.edu/samiam/

WebWEavr-III
WEBWEAVR-III is a Java application that supports the construction of Bayesian networks, inference in standard and dynamic Bayesian networks and decomposable Markov networks, construction and verification of multiply-sectioned Bayesian networks (MSBNs), inference in multi-agent MSBNs, and learning decomposable Markov networks.
http://www.cis.uoguelph.ca/~yxiang/ww3/

XBAIES
Rob Cowell's windows-based system for bayesian network inference and learning.
http://www.staff.city.ac.uk/~rgc/webpages/xbpage.html

XML Belief Network File Format
Proposed XML standard for describing Bayesian belief networks.
http://www.research.microsoft.com/dtas/bnformat/