LWB  
   Logics Workbench.
   http://www.lwb.unibe.ch/

SwitchMin Digital Circuit Minimizer  
   Tool for minimizing boolean logic functions.
   http://incolor.inetnebr.com/double/softlib/switchmin.html

PROTEIN  
   A PROver with a Theory Extension INterface. Theorem prover for first-order clause logic, written in ECRC's Prolog-dialect ECLiPSe. Free download, documentation.
   http://www.uni-koblenz.de/ag-ki/Implementierungen/Protein/

Bertrand  
   First-order satisfiability checker and prover for the Macintosh.
   http://www.humnet.ucla.edu/humnet/phil/grads/herzberg/Bertrand.html

Database of Existing Mechanized Reasoning Systems  
   A list (>50 entries) of automatic resolution provers (like Otter), interactive provers (like PVS) and other mechanized reasoning tools.
   http://www-formal.stanford.edu/clt/ARS/systems.html

Automated Reasoning Project  
   Web resource provided by research group. Includes access to software developed by the team, coverering such projects as FINDER (Finite Domain Enumerator), MaGIC (Matrix Generator for Implication Connectives) and Kripke (A theorem prover for the relevant
   http://cslab.anu.edu.au/ar/

MUltseq  
   A generic sequent prover for propositional finitely-valued logics.
   http://www.logic.at/multseq/

MUltlog  
   Takes as input the specification of a finitely-valued first-order logic and produces a sequent calculus, a natural deduction system, and clause formation rules for this logic.
   http://www.logic.at/multlog/

Isabelle  
   A generic theorem proving environment developed at Cambridge University (Larry Paulson) and TU Munich (Tobias Nipkow). Includes logic, documentation and free download.
   http://www.cl.cam.ac.uk/Research/HVG/Isabelle/

WinKE: A Proof Assistant for Teaching Logic  
   WinKE is an interactive proof assistant based on analytic tableaux, and designed for the teaching of deductive reasoning. Ordering information is available at this site, as are academic papers on the design of the software.
   http://www.dcs.kcl.ac.uk/staff/endriss/WinKE/

The Coq Project  
   Deals with effectively machine-checked formal mathematics. In practice, this includes the study of mathematical formalisms well-suited for implementations, the implementations themselves and the use of these for various applications. Focuses on software c
   http://pauillac.inria.fr/coq/

Logic Software from CSLI  
   By Jon Barwise and John Etchemendy.
   http://www-csli.stanford.edu/hp/Logic-software.html

ProofPower  
   A suite of tools supporting specification and proof in Higher Order Logic (HOL) and in Z notation.
   http://www.lemma-one.com/ProofPower/index/

LOOM  
   A language and environment for constructing intelligent applications. It is a research project in the Artificial Intelligence research group at the University of Southern California's Information Sciences Institute. The goal of the project is to develop
   http://www.isi.edu/isd/LOOM/LOOM-HOME.html

PVS  
   The PVS Specification and Verification System. Available for Sparc machines with Solaris 2 and Intel x86 Machines with Linux compatible with Redhat 5 or later. Required is Emacs (version 19 or later), recommended LaTeX and Tcl/Tk. Download by FTP.
   http://pvs.csl.sri.com/

Visual Turing  
   A graphical IDE for creating, running and debugging Turing machines. Freeware for Windows 95/98/NT/2000.
   http://www.cheransoft.com/vturing/

Tree Proof Generator  
   An implementation of the semantic tableaux method for classical propositional and predicate logic, written in JavaScript/DOM.
   http://www.umsu.de/logik/trees

ACL2 Version 2.7  
   A programming language in which you can model computer systems and a tool to help prove properties of those models. Available under GPL and runs on various platforms. Includes related download links.
   http://www.cs.utexas.edu/users/moore/acl2/

Gateway to Logic  
   A collection of web-based logic programs offering a number of logical functions: interactively or automatically build proofs, check theorems, and operate on propositional logic formulae.
   http://logik.phl.univie.ac.at/~chris/formular-uk.html

llprover  
   A linear logic prover that searches a cut-free proof for the given two-sided sequent of first-order linear logic.
   http://bach.scitec.kobe-u.ac.jp/llprover/

Paradox  
   A tool that processes first-order logic problems and tries to find finite-domain models for them; written by Koen Claessen and Niklas Sörensson. Haskell and C++; free download under GPL.
   http://www.cs.chalmers.se/~koen/paradox/

DELORES  
   A forward-chaining reasoning engine for defeasible logic, a less expressive but more efficient nonmonotonic logic.
   http://www.dfki.uni-kl.de/~miller/delores/

DC Proof Online  
   New proof-writing software to teach the fundamentals of logic and proof. Enables users/students to write error-free proofs by selecting rules of inference, axioms, etc. from convenient drop-down menus. Includes tutorial and exercises.
   http://www.dcproof.com

VeriFun  
   A semi-automated system for the verification of statements about programs written in a functional programming language. The system is capable of following fully-automated routines for theorem proving and hypotheses formation, as well as operating interact
   http://www.informatik.tu-darmstadt.de/pm/verifun/

Ludwig  
   Application that draws truth-tables for propositional logic formulae. Available for free download and web use.
   http://www.mintlogic.com/ludwig/

Proof General  
   Comprehensive Gnu-Emacs and XEmacs interface for several theorem provers including Coq, Isabelle, Lego, and Phox.
   http://proofgeneral.inf.ed.ac.uk

Church  
   Program understands the different types of lambda expressions, can extract lists of variables (both free and bound) and subterms, and can simplify complicated expressions. Uses Python.
   http://www.alcyone.com/software/church/