Best Why3 Alternatives in 2026
Updated
20 apps from formal verification tools ranked against Why3 on the same published basis.
- 1Why3 vs Lean
- 2Why3 vs Rocq
- 3Why3 vs Z3
- 4Why3 vs HOL4
- 5Why3 vs PVS
- 6Why3 vs Alloy Analyzer
- 7Why3 vs CBMC
- 8Why3 vs CPAchecker
- 9Why3 vs Isabelle
- 10Why3 vs NuSMV
- 11Why3 vs PRISM
- 12Why3 vs SPIN
- 13Why3 vs UPPAAL
- 14Why3 vs HOL Light
- 15Why3 vs ACL2
- 16Why3 vs Dafny
- 17Why3 vs Frama-C
- 18Why3 vs Stainless
- 19Why3 vs Ultimate Automizer
- 20Why3 vs Viper
Why3 alternatives compared
| # | App | Score | Free plan | From | Runs on |
|---|---|---|---|---|---|
| 1 | Lean | 6.7 | Free plan | Free | Linux, Mac, Web, Windows |
| 2 | Rocq | 6.7 | Free plan | Free | Browser, Linux, Mac, Web, Windows |
| 3 | Z3 | 6.7 | Free plan | Free | Android, API, Linux, Mac, self-hosted, Web, Windows |
| 4 | HOL4 | 6.6 | Free plan | Free | Linux, Mac, self-hosted, Windows |
| 5 | PVS | 6.6 | Free plan | Free | Linux, Mac, Windows |
| 6 | Alloy Analyzer | 6.5 | Free plan | Free | API, Linux, Mac, Windows |
| 7 | CBMC | 6.5 | Free plan | Free | Linux, Mac, self-hosted, Windows |
| 8 | CPAchecker | 6.5 | Free plan | Free | Linux, Mac, self-hosted, Windows |
| 9 | Isabelle | 6.5 | Free plan | Free | Linux, Mac, self-hosted, Windows |
| 10 | NuSMV | 6.5 | Free plan | Free | Linux, Mac, Windows |
| 11 | PRISM | 6.5 | Free plan | Free | Linux, Mac, Windows |
| 12 | SPIN | 6.5 | Free plan | Free | Linux, Mac, Windows |
| 13 | UPPAAL | 6.5 | Free plan | Free | Linux, Mac, Windows |
| 14 | HOL Light | 5.7 | No | — | Linux, Mac, self-hosted, Web, Windows |
| 15 | ACL2 | 5.6 | No | — | Linux, Mac, self-hosted, Windows |
| 16 | Dafny | 5.6 | No | — | Linux, Mac, self-hosted, Windows |
| 17 | Frama-C | 5.6 | No | — | Linux, Mac, Windows |
| 18 | Stainless | 5.6 | No | — | Linux, Mac, Windows |
| 19 | Ultimate Automizer | 5.6 | No | — | Linux, Web, Windows |
| 20 | Viper | 5.6 | No | — | Browser, Linux, Mac, Web, Windows |
Make your app an alternative to Why3
See the priceThe sponsored alternative slot on this page is labelled Sponsored.
Questions about Why3 alternatives
What is the best alternative to Why3?
Lean, number 1 in formal verification tools with a score of 6.7 out of 10. The others here: Rocq, Z3, HOL4 and 16 more.
What is the best free alternative to Why3?
Lean is the best-ranked alternative with a free plan. 13 of the 20 alternatives here publish a free plan on their own pricing pages.
How are these alternatives ranked?
Ranked free-and-open first: a usable free tier and open-source code, then the platforms it runs on and its documentation.