Blazing Agenda

Players with enough permissions upload their own costume textures, which then apply to specific mobs on the server. Costume textures must be PNG files of a set size, so a texture can be upscaled but not made arbitrarily large. Operators can upload, update and delete costumes, and players with the required permission can manage their own uploads through the Fashion Scrapbook.

A synced costume appears on mobs for every client that joins, without any setup on the other players' side beyond installing the mod. Because random uploads can carry questionable content, the mod only lets operators upload skins by default. Server owners can change the config and permissions to allow everybody, and each costume slot count and storage limit can also be adjusted there.

Blazing Agenda is client and server, so the server and every player need it. It requires Fabric API and oωo (owo-lib). The mod is open source under the GNU Lesser General Public License v3.0 only and is published for Fabric across 1.21 and 1.21.1, with 0.1.0+1.21.1 as the latest file for 1.21.1. A Change Look mobs resource pack is also required.