Prefab Editor - is Unity3d tool for editing prefabs in runtime(playmode). You can change anything in prefab instance (root object or any child) in runtime, then select changes you want to apply and press apply. It is just that simple.
For example, it is very convenient while editing a UI. You tweak positions, colors, and other properties of your elements and than you have to memorize changes (or write them down), press stop, find prefab and apply them again. With Prefab Editor you can just apply selectively changes you need.
Key Features
Also available on the Unity Store: https://assetstore.unity.com/packages/tools/utilities/prefab-editor-24895
RuntimePrefabEditor
folder somewhere under the Assets
folder.Window/Prefab Editor
.Apply Changes To Prefab
button.It was written few years ago and no longer developed. Though it should work quite well still and I hope someone will find it as useful as I once did.