Lean vs Why3
| Lean | Why3 | |
|---|---|---|
| Free plan | No | No |
| Free trial | No | No |
| Paid from | — | — |
| Open source | No | No |
| Platforms | Web, Windows, macOS, Linux | Web, Linux, Windows |
| Verification method | deductive | deductive |
| Supported formalisms | theorem-proving | contracts |
| Proof artifacts | Yes | — |
| Input languages | Lean 4 | WhyML, micro-C, micro-Python, MLCFG, Coma |
| Deployment | both | both |
| Counterexamples | — | Yes |
Both are listed in Best Formal Verification Tools. On The Geeks Club, Lean scores higher on our published basis.