Ultimate Outline Generator (Eevee & Cycles) is a Blender add-on from RUIDO VFX for producing crisp outlines on 2D, anime, and toon-style creations. It lets you control object thickness and apply stylized colors in a few clicks, and you can assign different outline thicknesses to individual objects.
Outlines are built with an inverted hull approach using a Solidify modifier, and the workflow is non-destructive, so you can edit or remove outlines without affecting the original mesh. A color index system assigns colors per object or updates several objects that share the same index at once, while a precise thickness slider controls outline width. When you no longer need an outline, clean removal strips all outline materials and modifiers.
The add-on uses an emission-based Universal Shader System compatible with both Eevee and Cycles, and it's built for fast, efficient workflows optimized for Eevee. It works with Blender 4+ and 5+, ships as a ready-to-install .zip, and includes an installation guide and user instructions. It's released under the GPL license.