Best Formal Verification Tools in 2026
Updated
In short: Rocq is ranked #1 of 33 as of 4 October 2026, ahead of Z3 and PVS. The best-ranked option with a free plan is Z3.
Checking that a system satisfies stated properties calls for tools whose languages, methods, and evidence fit the work at hand. Compare supported formalisms and input languages, then consider verification method and whether counterexamples or proof artifacts are available. Deployment, free-plan availability, and paid-from pricing offer additional points to weigh. Rocq, Z3, and PVS are among the entries to examine. The listed distinctions can help you assess how each tool aligns with the properties you need to verify and the kind of results or evidence your development process calls for.
33 formal verification tools ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
8 of the 25 here have a free tier you can use, 0 have open-source code on record, and 0 have full bars: free, open, on most of your devices and documented.
| # | App | Signal | Free tier | Open code | Devices | From | Score |
|---|---|---|---|---|---|---|---|
| 1 | RocqWeb · Windows · Mac · Linux · Extension | Three bars | — | 4 of 6 | Free | 6.7 | |
| 2 | Z3Web · Windows · Mac · Linux · Android · Self-hosted · API | Three bars | — | 5 of 6 | Free | 6.7 | |
| 3 | PVSWindows · Mac · Linux | Three bars | — | 3 of 6 | Free | 6.6 | |
| 4 | Alloy AnalyzerWindows · Mac · Linux · API | Three bars | — | 3 of 6 | Free | 6.5 | |
| 5 | CBMCWindows · Mac · Linux · Self-hosted | Three bars | — | 3 of 6 | Free | 6.5 | |
| 6 | IsabelleWindows · Mac · Linux · Self-hosted | Three bars | — | 3 of 6 | Free | 6.5 | |
| 7 | SPINWindows · Mac · Linux | Three bars | — | 3 of 6 | Free | 6.5 | |
| 8 | UPPAALWindows · Mac · Linux | Three bars | — | 3 of 6 | Free | 6.5 | |
| 9 | ACL2Windows · Mac · Linux · Self-hosted | Two bars | — | — | 3 of 6 | — | 5.6 |
| 10 | Frama-CWindows · Mac · Linux | Two bars | — | — | 3 of 6 | — | 5.6 |
| 11 | CPAcheckerWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.4 |
| 12 | cvc5Web · Windows · Mac · Linux | One bar | — | — | 4 of 6 | — | 5.4 |
| 13 | DafnyWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.4 |
| 14 | HOL LightWeb · Windows · Mac · Linux | One bar | — | — | 4 of 6 | — | 5.4 |
| 15 | LeanWeb · Windows · Mac · Linux | One bar | — | — | 4 of 6 | — | 5.4 |
| 16 | NuSMVWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.4 |
| 17 | PRISMWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.4 |
| 18 | StainlessWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.4 |
| 19 | ViperWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.4 |
| 20 | AgdaWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.3 |
| 21 | F*Windows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.3 |
| 22 | HOL4Windows · Linux | No signal | — | — | 2 of 6 | — | 5.3 |
| 23 | K FrameworkMac · Linux | No signal | — | — | 2 of 6 | — | 5.3 |
| 24 | OpenJMLWindows · Mac · Linux | One bar | — | — | 3 of 6 | — | 5.3 |
| 25 | SeaHornMac · Linux | No signal | — | — | 2 of 6 | — | 5.3 |
Is your app on this list?
Numbered spots on this list can be sponsored. They are labelled, and the editorial order and scores never change for payment.
Questions about this list
Which formal verification tool is ranked first on Freedom251?
Rocq is ranked #1 of 33 with a score of 6.7. Z3 is second and PVS third.
How many of these have a free plan?
8 of the 25 on this page publish a free plan on their own pricing pages.
How is this list ranked?
Ranked free-and-open first: a usable free tier and open-source code, then the platforms it runs on and its documentation. Paid placements never change a rank.