Best Why3 Alternatives in 2026
Updated
20 tools from formal verification tools ranked against Why3 on the same published basis.
- 1Why3 vs PVS
- 2Why3 vs Rocq
- 3Why3 vs Z3
- 4Why3 vs Alloy Analyzer
- 5Why3 vs UPPAAL
- 6Why3 vs CBMC
- 7Why3 vs Isabelle
- 8Why3 vs SPIN
- 9Why3 vs ACL2
- 10Why3 vs Frama-C
- 11Why3 vs Dafny
- 12Why3 vs Ultimate Automizer
- 13Why3 vs Lean
- 14Why3 vs CPAchecker
- 15Why3 vs HOL Light
- 16Why3 vs Viper
- 17Why3 vs cvc5
- 18Why3 vs NuSMV
- 19Why3 vs PRISM
- 20Why3 vs Stainless
Why3 alternatives compared
| # | Tool | Score | Free plan | From | Runs on |
|---|---|---|---|---|---|
| 1 | PVS | 7.5 | Free plan | Free | Linux, Mac, Windows |
| 2 | Rocq | 7.5 | Free plan | Free | Browser, Linux, Mac, Web, Windows |
| 3 | Z3 | 7.4 | Free plan | Free | Android, API, Linux, Mac, self-hosted, Web, Windows |
| 4 | Alloy Analyzer | 7.2 | Free plan | Free | API, Linux, Mac, Windows |
| 5 | UPPAAL | 7.2 | Free plan | Free | Linux, Mac, Windows |
| 6 | CBMC | 7.1 | Free plan | Free | Linux, Mac, self-hosted, Windows |
| 7 | Isabelle | 7.1 | Free plan | Free | Linux, Mac, self-hosted, Windows |
| 8 | SPIN | 7.1 | Free plan | Free | Linux, Mac, Windows |
| 9 | ACL2 | 7.0 | No | — | Linux, Mac, self-hosted, Windows |
| 10 | Frama-C | 6.9 | No | — | Linux, Mac, Windows |
| 11 | Dafny | 6.8 | No | — | Linux, Mac, self-hosted, Windows |
| 12 | Ultimate Automizer | 6.5 | No | — | Linux, Web, Windows |
| 13 | Lean | 6.4 | No | — | Web, Windows, Mac, Linux |
| 14 | CPAchecker | 6.3 | No | — | Windows, Mac, Linux |
| 15 | HOL Light | 6.3 | No | — | Web, Windows, Mac, Linux |
| 16 | Viper | 6.3 | No | — | Windows, Mac, Linux |
| 17 | cvc5 | 6.2 | No | — | Web, Windows, Mac, Linux |
| 18 | NuSMV | 6.2 | Free plan | Free | Linux, Mac, Windows |
| 19 | PRISM | 6.2 | No | — | Windows, Mac, Linux |
| 20 | Stainless | 6.2 | No | — | Windows, Mac, Linux |
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Questions about Why3 alternatives
What is the best alternative to Why3?
PVS, number 1 in formal verification tools with a score of 7.5 out of 10. The others here: Rocq, Z3, Alloy Analyzer and 16 more.
What is the best free alternative to Why3?
PVS is the best-ranked alternative with a free plan. 9 of the 20 alternatives here publish a free plan on their own pricing pages.
How are these alternatives ranked?
Ranked on what each maker publishes, the fullest spec sheet first: how deeply the product is documented, the platforms it runs on, a free tier or trial to test it, and its standing.