Best Free Blender Addons! Animation, Retopo, Modelling, Texturing

Secret Paint https://extensions.blender.org/add-ons/secret-paint/

Paint foliage on top of anything (select the object, select the surface, Q) Model procedural Architecture with Assemblies Create procedural Biomes Draw in 3D All in one shortcut "Q" (customizable)

Smear https://extensions.blender.org/add-ons/smear/

SMEAR is a 3D animation stylization Blender add-on, aimed at creation and customization of smear frames such as elongated in-betweens, multiple in-betweens and motion lines.

Ucupaint https://extensions.blender.org/add-ons/ucupaint/

Ucupaint is a Blender addon to manage texture layers for the Eevee and Cycles renderers. Already in development for years, Ucupaint provides a lot of easy-to-use features while also being able to fit into your usual shader nodes workflow.

MiraTools https://blenderartists.org/t/miratools/637385?u=peetie

MiraTools - modern modeling and retopology tools.

PolyQuilt Retopology Tool https://extensions.blender.org/add-ons/polyquilt-fork/

Its a tool to help speed up the process of manual hand retopology, similar to tools like Retopology Flow and Quad Draw.

EdgeFlow https://extensions.blender.org/add-ons/edgeflow/

This addon adds a set of operators which help when dealing with curved shaped meshes.

Core functionality aims at working with edge loops, but there are also a couple of tools which work on vertex selections too. The main workhorse is the set flow operator which helps to fit an edgeloop to the curvature of the surrounding mesh.