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Best F* Alternatives in 2026

Updated

20 tools from formal verification tools ranked against F* on the same published basis.

  1. 1
    Lean Free plan LinuxMacWebWin Free7.5
    F* vs Lean
  2. 2
    PVS Free plan LinuxMacWin Free7.5
    F* vs PVS
  3. 3
    Rocq Free plan extensionLinuxMacWebWin Free7.5
    F* vs Rocq
  4. 4
    Z3 Free plan AndroidapiLinuxMacself-hosted Free7.4
    F* vs Z3
  5. 5
    HOL4 Free plan LinuxMacself-hostedWin Free7.3
    F* vs HOL4
  6. 6
    Alloy Analyzer Free plan apiLinuxMacWin Free7.2
    F* vs Alloy Analyzer
  7. 7
    NuSMV Free plan LinuxMacWin Free7.2
    F* vs NuSMV
  8. 8
    UPPAAL Free plan LinuxMacWin Free7.2
    F* vs UPPAAL
  9. 9
    CBMC Free plan LinuxMacself-hostedWin Free7.1
    F* vs CBMC
  10. 10
    CPAchecker Free plan LinuxMacself-hostedWin Free7.1
    F* vs CPAchecker
  11. 11
    HOL Light LinuxMacself-hostedWebWin 7.1
    F* vs HOL Light
  12. 12
    Isabelle Free plan LinuxMacself-hostedWin Free7.1
    F* vs Isabelle
  13. 13
    PRISM Free plan LinuxMacWin Free7.1
    F* vs PRISM
  14. 14
    SPIN Free plan LinuxMacWin Free7.1
    F* vs SPIN
  15. 15
    ACL2 LinuxMacself-hostedWin 7.0
    F* vs ACL2
  16. 16
    Viper extensionLinuxMacWebWin 7.0
    F* vs Viper
  17. 17
    Frama-C LinuxMacWin 6.9
    F* vs Frama-C
  18. 18
    Stainless LinuxMacWin 6.9
    F* vs Stainless
  19. 19
    Dafny LinuxMacself-hostedWin 6.8
    F* vs Dafny
  20. 20
    K Framework apiLinuxMacself-hosted 6.8
    F* vs K Framework

F* alternatives compared

#ToolScoreFree planFromRuns on
1Lean7.5Free planFreeLinux, Mac, Web, Windows
2PVS7.5Free planFreeLinux, Mac, Windows
3Rocq7.5Free planFreeBrowser, Linux, Mac, Web, Windows
4Z37.4Free planFreeAndroid, API, Linux, Mac, self-hosted, Web, Windows
5HOL47.3Free planFreeLinux, Mac, self-hosted, Windows
6Alloy Analyzer7.2Free planFreeAPI, Linux, Mac, Windows
7NuSMV7.2Free planFreeLinux, Mac, Windows
8UPPAAL7.2Free planFreeLinux, Mac, Windows
9CBMC7.1Free planFreeLinux, Mac, self-hosted, Windows
10CPAchecker7.1Free planFreeLinux, Mac, self-hosted, Windows
11HOL Light7.1No—Linux, Mac, self-hosted, Web, Windows
12Isabelle7.1Free planFreeLinux, Mac, self-hosted, Windows
13PRISM7.1Free planFreeLinux, Mac, Windows
14SPIN7.1Free planFreeLinux, Mac, Windows
15ACL27.0No—Linux, Mac, self-hosted, Windows
16Viper7.0No—Browser, Linux, Mac, Web, Windows
17Frama-C6.9No—Linux, Mac, Windows
18Stainless6.9No—Linux, Mac, Windows
19Dafny6.8No—Linux, Mac, self-hosted, Windows
20K Framework6.8No—API, Linux, Mac, self-hosted
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Questions about F* alternatives

What is the best alternative to F*?

Lean, number 1 in formal verification tools with a score of 7.5 out of 10. The others here: PVS, Rocq, Z3 and 16 more.

What is the best free alternative to F*?

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 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.