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Apalache
What Apalache is
Apalache is a free, open-source symbolic model checker for TLA+ specifications, with Quint input support and self-hosted deployment. It translates TLA+ into logic handled by SMT solvers, using Z3 by default and listing CVC5 as experimental. Analysis options include randomized symbolic execution, bounded model checking, inductiveness checking, and custom exploration scripts over symbolic actions. Documented commands cover parsing, type checking, simulation, bounded checking, and testing a single action. Quint, Solarkraft, and Atomkraft use Apalache as a backend model checker. You can run it from a prebuilt JVM package, a Docker image, or a source build. The installation guide recommends at least 4 GB of memory, with actual needs depending on the solver and specification. Bounded checking can miss bugs requiring longer executions than the selected length. Statistics are off by default, while opting in sends anonymized run statistics to tlapl.us. Apalache is Apache-2.0 licensed.
Who it suits
It suits developers and verification teams working with TLA+ or Quint specifications who want symbolic analysis on Linux, through an API, or in a self-hosted setup.
What it does well
- Free and open-source Apache-2.0 software
- Supports TLA+ and Quint inputs
- Multiple symbolic analysis methods
- Runs via JVM package, Docker, or source
- Counterexamples supported
What to know first
- At least 4 GB memory recommended
- Bounded checks can miss longer-execution bugs
- CVC5 support is experimental
- Opt-in statistics are sent per run
Verdict
Apalache provides several symbolic checking modes and flexible deployment choices for TLA+ and Quint work. Review its memory needs and bounded-checking limits before relying on a particular analysis.
Facts from Apalache's own pages
- Analysis methods
- It supports randomized symbolic execution, bounded model checking, and inductiveness checking. · apalache-mc.org, 11 Oct 2026
- Analysis modes
- It supports randomized symbolic execution, bounded model checking, inductiveness checking, and custom exploration scripts over symbolic actions. · apalache-mc.org, 11 Oct 2026
- Bounded-checking limit
- Bounded model checking can miss a bug if it requires an execution longer than the specified checking length. · apalache-mc.org, 11 Oct 2026
- Commands
- The documented commands include parsing, type checking, simulation, bounded checking, and testing a single action. · apalache-mc.org, 11 Oct 2026
- Installation
- The documentation describes running Apalache from a prebuilt JVM package, with Docker, or by building from source. · apalache-mc.org, 11 Oct 2026
- License
- The repository identifies Apalache as Apache-2.0 licensed. · github.com, 11 Oct 2026
- Memory
- The documentation recommends allocating at least 4GB of memory, with requirements depending on the solver and specification. · apalache-mc.org, 11 Oct 2026
- Memory guidance
- The installation guide recommends allocating at least 4 GB of memory, with required memory depending largely on the solver and specification. · apalache-mc.org, 11 Oct 2026
- Other uses
- Solarkraft and Atomkraft use Apalache as a backend model checker for their respective tools. · apalache-mc.org, 11 Oct 2026
- Purpose
- Apalache is a symbolic model checker for TLA+ specifications. · apalache-mc.org, 11 Oct 2026
- Quint
- Quint uses Apalache as a backend model checker. · apalache-mc.org, 11 Oct 2026
- Related tools
- Solarkraft and Atomkraft use Apalache as a backend model checker. · apalache-mc.org, 11 Oct 2026
- Release
- The GitHub releases page lists version 0.62.3, dated 2026-10-01. · github.com, 11 Oct 2026
- Run options
- The documentation describes running Apalache from a prebuilt package in the JVM, from a Docker image, or by building from source. · apalache-mc.org, 11 Oct 2026
- SMT solvers
- Apalache translates TLA+ into logic supported by SMT solvers such as Microsoft Z3. · apalache-mc.org, 11 Oct 2026
- SMT translation
- It translates TLA+ into logic supported by SMT solvers such as Microsoft Z3. · apalache-mc.org, 11 Oct 2026
- Solver options
- The documented solver choices are Z3 by default and cvc5 as experimental. · apalache-mc.org, 11 Oct 2026
- Solver support
- The documentation lists Z3 as the default SMT solver and CVC5 as experimental. · apalache-mc.org, 11 Oct 2026
- Statistics
- Statistics collection is off by default; opting in submits anonymized statistics to tlapl.us on every run. · apalache-mc.org, 11 Oct 2026
- Support
- The site names Igor Konnov as the contact person. · apalache-mc.org, 11 Oct 2026
- Support and community
- The project README directs users to the Apalache Forum for discussion and to the project for contributions. · github.com, 11 Oct 2026
- Telemetry
- Statistics collection is off by default; opting in submits anonymized statistics for each run to tlapl.us. · apalache-mc.org, 11 Oct 2026
Where Apalache stands on Freedom251
- Formal Verification Tools#13 of 34