The 3.1.1 version of Icon Converter for Mac is available as a free download on our website. The program lies within Theming Tools, more precisely Icons & cursors.
From the developer:
With Icon Converter , you now have the option to convert to four different formats. The Mac ICNS format allows you to customize the icons of applications and folders on your Mac. Mac PNG format can be used to create a folder of resized PNG icons for Xcode Image Assets.
You may want to check out more Mac applications, such as Image to icon, iConvert Icons or Icon Bot, which might be similar to Icon Converter.