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Alloy Analyzer
alloytools.org
What it is
Alloy Analyzer is a free model-checking tool for describing systems in the Alloy language and exploring the structures those descriptions permit. It searches for structures that satisfy constraints and for counterexamples to properties. Models can represent collections of structures that change over time, including security configurations and switching network topologies. The Analyzer presents results graphically, with appearance options that can be tailored to a domain. Alloy 6 adds mutable state, temporal logic, and temporal model checking; that checking requires NuSMV or nuXmv to be installed and available in PATH. The self-contained executable includes the Pardinus/Kodkod model finder, SAT solvers, the standard Alloy library, tutorial examples, and source code. The same JAR can be used as an API in other applications. Sterling adds a web-based visualizer with graph and table views, customizable and extendable with JavaScript. Alloy is self-hosted, supports Linux, macOS, Windows, and API use, and is maintained by volunteers.
Spec sheet
- Purpose
- Alloy is a language for describing evolving structures, and the Alloy Analyzer explores models by finding structures that satisfy constraints or counterexamples to properties.Read 4 Oct 2026 · alloytools.org
- Platforms
- The download page identifies Alloy 6.2.0 and says it includes a version for macOS High Sierra; it also describes running the JAR with Java.Read 4 Oct 2026 · alloytools.org
- API
- The same JAR file can be incorporated into other applications to use Alloy as an API.Read 4 Oct 2026 · alloytools.org
- Applications
- The project links applications including Alloy*, a Ruby embedding, a bounded Java verifier, and a firewall security policy analyzer.Read 4 Oct 2026 · alloytools.org
- Bundled components
- The self-contained executable includes the Pardinus/Kodkod model finder, SAT solvers, the standard Alloy library, tutorial examples, and source code.Read 4 Oct 2026 · alloytools.org
- Community support
- The project is maintained by volunteers, with Discourse as its main discussion venue and Stack Overflow as the venue for precise questions monitored by developers.Read 4 Oct 2026 · alloytools.org
- Modeling
- Alloy models describe sets of structures that may evolve over time, such as security configurations or switching network topologies.Read 4 Oct 2026 · alloytools.org
- Origin
- Alloy was created in MIT's Software Design Group.Read 4 Oct 2026 · alloytools.org
- Release
- The site lists Alloy 6.2.0 as the latest release, dated 2025-01-09.Read 4 Oct 2026 · alloytools.org
- Security use
- The project says Alloy has been used to find holes in security mechanisms and describes modeling security configurations of web applications as an example.Read 4 Oct 2026 · alloytools.org
- Temporal analysis
- Alloy 6 adds mutable state, temporal logic, and temporal model checking; the latter relies on NuSMV or nuXmv installed by the user and available in PATH.Read 4 Oct 2026 · alloytools.org
- Visualization
- The Analyzer displays structures graphically, and their appearance can be customized for the domain.Read 4 Oct 2026 · alloytools.org
- Visualizer extension
- Sterling is a web-based Alloy visualizer customizable and extendable with JavaScript, with graph and table views.Read 4 Oct 2026 · alloytools.org
Plans and prices
Alloy Analyzer Free Open source project · self-contained executable Read 4 Oct 2026 · alloytools.org
Strong points and limits
Strong points
- Free, self-contained executable with examples and source code
- Finds structures and counterexamples from Alloy models
- Graphical results can be customized for a domain
- JAR can be incorporated into other applications
- Runs on Linux, macOS, and Windows
Limits
- Temporal checking requires NuSMV or nuXmv installed separately
- Project is maintained by volunteers
Who it suits
Alloy suits people modeling systems with constraints or changing states, including security configurations and network topologies. It also fits developers who want to embed the JAR or use its model-checking capabilities in their own applications.
Verdict
Alloy Analyzer combines constraint-based model exploration with counterexample finding and graphical inspection. Its bundled components make it usable as a standalone tool, while temporal checking has an additional NuSMV or nuXmv dependency.
Where Specifiction places it
- Formal Verification Tools#5 of 358.2
