Lean
6.9#1 in formal verification toolsFree planFree planWebLinuxmacOSWindows
VisitLean vs TLA+
What both publish
| Fact | Lean | TLA+ |
|---|---|---|
| Editor integration | The recommended setup uses VS Code and the official Lean 4 extension, which provides syntax highlighting and code completion. | A Visual Studio Code extension supports TLA+ and PlusCal syntax highlighting, translation, parsing, TLC runs, result visualization, code completion, and formatting. |
| 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 TLA+ tools and Toolbox repository 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 Toolbox download instructions cover Windows, Mac OS, and Linux. |
| Proof checking | Lean's minimal trusted kernel is described as guaranteeing correctness in mathematical proof, software verification, and hardware verification. | TLAPS mechanically checks proofs written in TLA+. |
| Support | The Lean Community Zulip is described as the central hub for questions and collaboration, and Lean FRO hosts weekly technical office hours. | The TLA+ Foundation directs technical questions and issues to the appropriate GitHub issue tracker. |
Lean plans
- Lean 4Free
TLA+ plans
- TLA+Free
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 TLA+ if…
TLA+ suits teams modeling concurrent or distributed systems and checking designs before implementation. It offers both model-checking and proof-checking workflows, with interfaces for the Toolbox, VS Code, and command line.