IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
LiteIcon - LiteIcon is a simple app which allows you to change your system icons quickly and easily.
IconWorkshop - Application to create and manage software icons. A must for developers.
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.
IconLover - Icon editor for Windows.
JDraw - Open Source SF.net