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.
LiteIcon - LiteIcon is a simple app which allows you to change your system icons quickly and easily.
Icon Generator - Icon Generator is a little application built on AIR that lets you generate a CS5 or Web 2.
Pictogram - Customize macOS app icons with ease