Best Stainless Alternatives in 2026
Updated
20 apps from formal verification tools ranked against Stainless on the same published basis.
- 1Stainless vs Lean
- 2Stainless vs Rocq
- 3Stainless vs Z3
- 4Stainless vs HOL4
- 5Stainless vs PVS
- 6Stainless vs Alloy Analyzer
- 7Stainless vs CBMC
- 8Stainless vs CPAchecker
- 9Stainless vs Isabelle
- 10Stainless vs NuSMV
- 11Stainless vs PRISM
- 12Stainless vs SPIN
- 13Stainless vs UPPAAL
- 14Stainless vs HOL Light
- 15Stainless vs ACL2
- 16Stainless vs Dafny
- 17Stainless vs Frama-C
- 19Stainless vs Ultimate Automizer
- 20Stainless vs Viper
- 21Stainless vs K Framework
Stainless 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 |
| 19 | Ultimate Automizer | 5.6 | No | — | Linux, Web, Windows |
| 20 | Viper | 5.6 | No | — | Browser, Linux, Mac, Web, Windows |
| 21 | K Framework | 5.5 | No | — | API, Linux, Mac, self-hosted |
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Questions about Stainless alternatives
What is the best alternative to Stainless?
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 Stainless?
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.