I’ve just developed a little sandbox for quick shader prototyping!
You can write code, test and iterate without distractions. It could be also useful to play around code from the community within a safe environment.
It has goodies like full syntax highlighting for the Godot 4 shader languege, error status bar and widgets for the most common uniform datatypes.
Full source code and binaries are available on the github: GitHub - horologiq/Godot-Shaders-Sketchbook: App for quick prototyping Godot shaders
Or you can try it on the browser directly: https://horologiq.itch.io/godot-shaders-sketchbook