cvc5

cvc5 is a free, open-source theorem prover for developers and researchers working on formal verification or solver-backed synthesis. It is strongest when a workflow needs satisfiability checks across several mathematical theories, either from the command line or embedded in software. Its breadth and APIs are compelling; the optional GPLv3 dependencies are the licensing point to examine before combining it with other code.

Overview

cvc5 decides whether first-order formulas are satisfiable or valid across combinations of background theories. It also includes a Syntax-Guided Synthesis engine that synthesizes functions subject to theory-based constraints. That makes it useful both as a verification component and in systems that need to generate functions from specifications. It is a focused solver, not a general-purpose interactive proof assistant.

Use it as a standalone command-line program or as a library. The project names Kind 2, QMaxUSE, and TRLC among tools that use cvc5 as a backend or for verification checks. Proofs and unsatisfiable cores can help explain unsatisfiability results, an important advantage when a bare yes-or-no answer is not enough.

Key features

Theories, inputs, and APIs

Its standardized SMT-LIB theory support covers arrays, bit-vectors, floating-point numbers, integer and real arithmetic, mixed-integer arithmetic, and strings, alongside nonstandard and extended theories. This range is useful for problems that combine different mathematical domains. The command-line binary accepts SMT-LIB v2 and SyGuS-IF, while documented APIs include C++, C, Java, and Python, including a Pythonic API. Those interfaces give teams a choice between running solver scripts directly and integrating solver calls into their own applications.

New users are directed toward prebuilt Linux, macOS, and Windows binaries, and source releases are also provided. The project homepage links to an online interface for running SMT-LIB scripts, which offers a way to try the solver through a web browser. The documented API and language list spans more than the binary download platforms, but the strongest fit is for teams comfortable working with formal inputs or programming interfaces.

Robustness and support

The development team aims for high robustness in core use without experimental options. It also says it gives user-reported bugs priority over fuzzer findings, explaining that tradeoff by the small size of the team. Bug reports go to the issue tracker; questions, feature requests, and contributions are directed to GitHub Discussions. This is a sensible support route for a community-led tool, though it is not a promise of commercial support or response times.

Pricing

cvc5 costs nothing. The free offering is the open-source solver, with no separate free-trial period or paid tier described. Its use as a standalone tool or library is permitted with essentially no limit on research or commercial use, making it viable for both academic work and commercial applications.

The default modified BSD license is permissive for many integrations, but optional GPLv3 dependencies change the license of the resulting combined work to GPLv3. Organizations embedding cvc5 should review which dependencies they include and whether that licensing condition fits their distribution plans.

Platforms

cvc5 supports Linux, macOS, and Windows downloads, plus API, self-hosted, and web use. The range suits teams that want local binaries, deployment in their own environment, library integration, or a browser-based first look. Its deployment options favor technical users who can work with solver inputs and configure a software workflow around them.

Who it's for

Choose cvc5 if you need an SMT solver for formal verification, theorem-proving workflows, or function synthesis, and want control over using it as a command-line tool or library. It is particularly attractive when your formulas span multiple supported theories or when proof artifacts and unsatisfiable cores matter. Look elsewhere if you need an interactive proof assistant rather than an automatic solver, or if the optional dependency licensing conflicts with your product's distribution model.

Pros and cons

Broad theory coverage: Standard support for arrays, bit-vectors, floating-point, arithmetic, and strings helps with formulas that cross domain boundaries.

More than a decision result: Proofs and unsatisfiable cores can make unsatisfiability results easier to inspect and explain.

Flexible integration: Command-line inputs and C++, C, Java, and Python APIs support both direct solver use and embedding.

Licensing needs attention: Optional GPLv3 dependencies make the combined work subject to GPLv3, despite the modified BSD default license.

Focused audience: Its formal inputs and solver-oriented purpose make it a poor fit for users seeking a general interactive proof environment.

Alternatives

Formal Verification Tools is a useful category to browse if you want to compare options across the field.

Lean is worth considering if you want a theorem-proving environment rather than cvc5's automatic SMT-solving and synthesis focus.

PVS offers a noncommercial free plan and a separate commercial plan with custom pricing; consider it if those terms suit your use case.

Rocq is another free theorem prover and dependently typed programming language, distributed under the GNU Lesser General Public License.

Why3 is a free alternative with API, self-hosted, and web platforms, distributed under the GNU Lesser General Public License with a special linking exception.

Z3 is a free, MIT-licensed solver option if that license is a priority.

Boogie may suit a workflow that can meet its.NET requirement and provide a supported SMT solver.

HOL4 is another free formal tool, under a modified three-clause BSD license.

Alloy Analyzer is a free, open-source option distributed as a self-contained executable.

Verdict

cvc5 is a strong choice for developers and researchers who need automatic solving across a broad set of theories, synthesis, and interfaces for either standalone or embedded use. Its main advantage is the combination of theory coverage and practical integration options at no cost. Check the optional GPLv3 dependency implications before adopting it in a combined work; if those terms do not fit, choose a solver whose licensing works for your distribution plans.