Lean vs Z3
Lean
lean-lang.orgZ3
github.comSide by side
| Figure | Lean | Z3 |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| Android | — | Yes |
| API | — | Yes |
| Self-hosted | — | Yes |
| Plans published | 1 | 1 |
| Spec score · Formal Verification Tools | 8.6 (#2) | 7.4 (#26) |
| Browser use | The learning page links to Lean4Web, described as a web-based version that runs Lean code in a browser. | The project wiki links to a page for trying Z3 in a browser. |
| 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. | The repository states that Z3 is licensed under the MIT license. |
| Platforms | The reference lists Linux, macOS, and Windows among Lean’s supported platforms, with Tier 1 binary releases available through elan. | The project wiki lists Windows, OSX, Linux (Ubuntu and Debian), and FreeBSD as supported platforms. |
| 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 wiki says to contact the creator of an external binding package for support issues. |
Plans
In their own words
Lean
Lean is an open-source programming language and proof assistant for formalizing mathematics, verifying software, and writing general code. Its minimal trusted kernel checks proofs, and the project describes it as supporting correctness in mathematical, software, and hardware verification. Lean includes the Grind tool for automating some pattern matching, case analysis, and systems of linear inequalities; metaprogramming lets users add notation and proof automation. Projects are managed with Lake, the package manager bundled with Lean. Mathlib is a community-driven library with over a million lines spanning areas including algebra, analysis, topology, probability, and computer science. The recommended setup uses VS Code with the Lean 4 extension for syntax highlighting and code completion, while Neovim with lean.nvim is also well-supported. Lean runs on Linux, macOS, and Windows, and Lean4Web lets users run code in a browser. The software is free under the Apache 2.0 license. Learning resources include textbooks, tutorials, interactive games, documentation, and an API reference.
Z3
Z3 is a theorem prover and satisfiability modulo theories (SMT) solver used in software verification and analysis. SMT-LIB2 is its default input format, and it supports the SMT-LIB format. The project documents bindings or APIs for C, C++, .NET, Java, Go, OCaml, Python, Julia, and JavaScript/TypeScript. Z3 can be built with CMake, vcpkg, or Bazel, and the repository links to pre-built binaries for stable and nightly releases. A project wiki also links to a page for trying Z3 in a browser. It supports proof artifacts and counterexamples, and listed input languages include SMT-LIB2, Rust, Smalltalk, and several of the languages with documented APIs. Z3 is MIT licensed, with downloads and source code available at no charge. Python is required to build it; additional toolchains are needed for Java, .NET, OCaml, and Julia APIs. The README says MSVC builds enable Control Flow Guard and Address Space Layout Randomization by default.