Lean
6.9#1 in formal verification toolsFree planFree planWebLinuxmacOSWindows
VisitLean vs Why3
What both publish
| Fact | Lean | Why3 |
|---|---|---|
| Extensibility | Lean's metaprogramming capabilities let users add domain-specific notation and proof automation. | Why3 can be extended with support for new external provers and used as a software library through its API. |
| License | Lean is released under the Apache 2.0 license, which the documentation describes as allowing others to use and extend the code and mathematical libraries freely. | TryWhy3 is distributed under the GNU Lesser General Public License version 2.1 with a special linking exception. |
| Support | The Lean Community Zulip is described as the central hub for questions and collaboration, and Lean FRO hosts weekly technical office hours. | The project provides a user mailing list, a Zulip chat, and a bug tracking system. |
Lean plans
- Lean 4Free
Why3 plans
- Why3Free
Pick Lean if…
Lean suits programmers, theorem provers, and mathematicians working with formalization, proof checking, or software verification. Its general coding capability and browser version may also suit users exploring Lean before choosing a local setup.
Pick Why3 if…
Why3 suits developers and researchers working on deductive verification with contracts and WhyML. It may also fit users who need to connect external provers or use its OCaml API.