b3dsdf (blender signed distance functions) is a toolkit of 2D/3D signed distance functions and operators nodegroups for the shader editor in Blender 2.83+.
These nodes can be used by appending from the .blend file or use them with the addon which adds a menu in the shader editor. They can also be used with the asset browser by adding the .blend as an asset library and marking them as assets.
As of D15198 it's also possible to use the SDF nodes/operators from this pack via their Geometry Nodes equivalents in Blender 3.3 or above (more details)
Currently there are no plans to maintain another set of nodes/add-on but they can be converted for use with the blender booster add-on by Val Barashkov.
Download the latest zip file from the release page and install as normal. There's no need to unzip before installing. You might have to restart Blender for changes to take effect after installing / uninstalling.
Alternatively you have the option to install directly from source (code > download zip, or via repo cloning) which might include new features/nodes.
List of available nodegroups can be found in shader_nodes.json. Examples (with images) can be found in the wiki page (work in progress).