Selects all UV islands on one UDIM is a Blender add-on for working with UDIM layouts. It lets you select all islands and shells, along with their corresponding faces, that belong to a single chosen UDIM, UV-space or UV-tile.
To use it, pick an island or shell of the UDIM you want inside the UV Editor and press Alt+L, or choose the matching entry under UV Editor > Select > Select UDIM Faces & Islands. A demo video for the add-on is available online.
Version 1.2.0 added support for Blender 5.0 and fixed a bug affecting negative UDIM regions with negative coordinates. The add-on is compatible with Blender 4.2 LTS and newer, requires no special permissions, and is released under the GNU General Public License v3.0 or later. It has been downloaded more than 23,000 times from the Blender Extensions library.