Jape 7.0 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program is included in Productivity Tools. We recommend checking the downloaded files with any free antivirus. This free software for Mac OS X was originally created by Richard Bornat, Sufrin.
From the developer:
Jape is a configurable graphical formal-proof calculator. It's possible to define a logic, decide how your users will view their proofs, and much more. It works with variants of the sequent calculus and natural deduction, as well as functional programming theories and theories of operational semantics.
You may want to check out more software for Mac, such as JonDo or Armok Vision, which might be related to Jape.