LiteIcon - LiteIcon is a simple app which allows you to change your system icons quickly and easily.
IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
Replacicon - Just updated to macOS Big Sur? You may have noticed some of the apps in your Dock look a bit inconsistent with the rest of the system.
Icon Slate - Icon Slate lets you easily compose, import and export desktop icons in many formats.
Icono Maker - Icono Maker is an icon maker for Windows.
IconWorkshop - Application to create and manage software icons. A must for developers.