Lean FRO maintains a tightly focused portfolio built around the Lean programming language and its ecosystem. Elan, the companion version manager, lets researchers and software engineers install, switch, and update multiple Lean toolchains without manual path editing, mirroring the convenience familiar to Rust and Node.js developers. Lean itself is a functional language designed for writing correct-by-construction code and machine-checked mathematical proofs; its expressive dependent type system allows the same codebase to serve as runnable software and as a formal specification that can be verified by an automated theorem prover. Typical use cases range from cryptography libraries whose security properties are mathematically certified, to compilers whose optimization passes are proven to preserve semantics, to academic projects that digitize centuries of mathematical knowledge into searchable, machine-verifiable libraries. Because Lean also compiles to efficient native or C code, teams can ship high-assurance components embedded in larger systems written in C++, Rust, or Go. The toolchain integrates with Visual Studio Code, Emacs, and Vim through the Language Server Protocol, offering real-time proof state feedback, incremental compilation, and goal-driven interactive tactics. Lean FRO’s software is available for free on get.nero.com, where downloads are delivered through trusted Windows package sources such as winget, always resolve to the newest upstream release, and can be installed individually or in a single batch command.