The 4.1 version of LTspice for Mac is available as a free download on our website. The application is included in System Tools. The most popular version among LTspice for Mac users is 4.1. The default filename for the program's installer is ltspiceiv.dmg. The actual developer of this free software for Mac is Linear Technology.
From the developer:
LTspice IV is a high performance SPICE simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators. The enhancements to SPICE have made simulating switching regulators extremely fast compared to normal SPICE simulators, allowing the user to view waveforms for most switching regulators in just a few minutes.
You may want to check out more Mac applications, such as SubCleaner, dmgCreator or Application Wizard Installer, which might be related to LTspice.