Project Cleaner

Non-distracting, dockable UI (works best docked).
Enhanced Project view:
Unused files highlighted RED.
Counters for unused assets & scenes on folders.
Sizes of unused assets & scenes shown on files and folders.
Editor Dark skin support.
Actions for unused files:
Clean single asset/scene.
Clean by folder.
Multiselect cleanup (all combinations supported).
Customization:
Ignored folders list.
Ignore Materials & ScriptableObjects.
Custom background color for unused files (default: red).

Search References

Blazing fast; usage changes are instantly displayed.
Find references/usages/relationships in Project or Scene:
Nested Prefabs supported.
All asset types supported, incl. AnimatorController states.
Explore usages & refs:
Lock view.
Back/Forward navigation with Ctrl+Z / Ctrl+Y.
Mouse hotkeys support.

Support & Docs

Top-notch support — responses in under 12 hours (via publisher support link)
FAQ / Quick answers — external document (link provided)

Asset Cleaner PRO - Clean | Find References