Leon System for Verification, Synthesis and Repair

The One, Leon Way

Leon is an automated system for verifying, repairing, and synthesizing functional Scala programs.

The system can be tried out online, with no installation required, at the following link:


Leon source code is publicly available on github:


The github repository contains the documentation that can be built in various formats, including in particular HTML.

A snapshot of this documentation, including a tutorial, is also available from http://leon.epfl.ch, please check