Cryptocat 3.2.07 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. Cryptocat works fine with Mac OS X 10.7 or later.
The actual developer of this free software for Mac is Nadim Kobeissi and the Cryptocat Project. The most popular version among the application users is 2.2. The application relates to Communication Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
Cryptocat is free, open chat that aims to provide an open, accessible Instant Messaging environment with a transparent layer of encryption that's easy to use. Easily have group conversations with your friends without fearing monitoring or interception.
Cryptocat is developed by privacy advocates, for privacy advocates.
You may want to check out more software for Mac, such as Dialectic, Blink or AeroFS, which might be similar to Cryptocat.
Instant messaging