Why3 vs Z3
| Why3 | Z3 | |
|---|---|---|
| Free plan | Yes | Yes |
| Free trial | No | No |
| Paid from | Free | Free |
| Open source | No | No |
| Platforms | api, Linux, self-hosted, Web, Windows | Android, api, Linux, macOS, self-hosted, Web, Windows |
| Verification method | deductive | — |
| Supported formalisms | contracts | theorem-proving |
| Counterexamples | Yes | Yes |
| Input languages | WhyML, micro-C, micro-Python, MLCFG, Coma | SMT-LIB2, C, C++, .NET, Java, Python, Rust, OCaml, Julia, JavaScript, TypeScript, Smalltalk, Go |
| Deployment | both | self-hosted |
| Free plan | — | Yes |
| Proof artifacts | — | Yes |
Both are listed in Best Formal Verification Tools. On Freedom251, Z3 scores higher on our published basis.