Download of Acheron 0.9.0 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free Mac application is Michael Bohn. Acheron for Mac lies within Developer Tools, more precisely IDE.
From the developer:
Acheron is a compiler that translates Common Lisp source code to JavaScript source code. The code can than be executed natively in any modern webbrowser. Programs are written in a subset of CL and after compilation executed in a webbrowser. This app has native functions that are written in JS and are the bridge between CL and JS.
You may want to check out more software for Mac, such as PowerGlot, ChIDE or EcoLab, which might be similar to Acheron.