Best Formal Verification Tools in 2026
Updated
33 formal verification tools ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
33ranked
0free plans on this page
9 Oct 2026last checked
Input list Formal Verification Tools 8 channels on this page · 37 of 64 spec lines stated by the makers
Ch Tool Free planPaid fromVerification methodSupported formalismsCounterexamplesProof artifactsInput languagesDeployment Spec sheet Score
26 VeriFast Free plannot statedPaid fromnot statedVerification methodsymbolicSupported formalismscontractsCounterexamplesnot statedProof artifactsnot statedInput languagesC, Rust, JavaDeploymentself-hosted 4/8spec lines stated 6.1
27 Why3 Free plannot statedPaid fromnot statedVerification methoddeductiveSupported formalismscontractsCounterexamplesYesProof artifactsnot statedInput languagesWhyML, micro-C, micro-Python, MLCFG, ComaDeploymentboth 5/8spec lines stated 6.1
28 Agda Free plannot statedPaid fromnot statedVerification methoddeductiveSupported formalismstheorem-provingCounterexamplesnot statedProof artifactsnot statedInput languagesAgdaDeploymentself-hosted 4/8spec lines stated 6.0
29 F* Free plannot statedPaid fromnot statedVerification methodhybridSupported formalismstheorem-provingCounterexamplesnot statedProof artifactsnot statedInput languagesF*Deploymentself-hosted 4/8spec lines stated 6.0
30 SeaHorn Free plannot statedPaid fromnot statedVerification methodhybridSupported formalismsinvariantsCounterexamplesYesProof artifactsnot statedInput languagesC, LLVM IRDeploymentself-hosted 5/8spec lines stated 5.9
31 Satisfiability.jl Free planYesPaid fromnot statedVerification methodsymbolicSupported formalismstheorem-provingCounterexamplesnot statedProof artifactsnot statedInput languagesJulia; SMT-LIBDeploymentself-hosted 5/8spec lines stated 5.7
32 Apalache Free plannot statedPaid fromnot statedVerification methodsymbolicSupported formalismsinvariantsCounterexamplesYesProof artifactsnot statedInput languagesTLA+, QuintDeploymentself-hosted 5/8spec lines stated 5.6
33 Romeo Free planYesPaid fromnot statedVerification methodmodel-checkingSupported formalismstemporal-logicCounterexamplesnot statedProof artifactsnot statedInput languagesTimed Petri NetsDeploymentself-hosted 5/8spec lines stated 5.6
Compare all 8 in a table
| # | Tool | Score | Free plan | Free plan | Paid from | Verification method | Supported formalisms |
|---|---|---|---|---|---|---|---|
| 26 | VeriFast | 6.1 | No | — | — | symbolic | contracts |
| 27 | Why3 | 6.1 | No | — | — | deductive | contracts |
| 28 | Agda | 6.0 | No | — | — | deductive | theorem-proving |
| 29 | F* | 6.0 | No | — | — | hybrid | theorem-proving |
| 30 | SeaHorn | 5.9 | No | — | — | hybrid | invariants |
| 31 | Satisfiability.jl | 5.7 | No | Yes | — | symbolic | theorem-proving |
| 32 | Apalache | 5.6 | No | — | — | symbolic | invariants |
| 33 | Romeo | 5.6 | No | Yes | — | model-checking | temporal-logic |
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