JelloUI is an independent client-side UI platform and prerequisite mod for Minecraft Fabric 26.2.
It provides a reusable, versioned public API for polished Jello-style interfaces: screens, ClickGUI content, HUDs, notifications, themes, TrueType typography, animation and easing, profiles, keybinds, world-space rendering helpers, and Music Player / Music Manager.
JelloUI itself contains no gameplay modules. Install it when another mod depends on its API, or when you want the core Jello interface without gameplay features.
The separate JelloUI Official Addon(Coming soon) restores the first-party Jello GUI modules. Third-party mods can also register their own screens, modules, HUDs and world markers through the public API.

Music playback requires yt-dlp. JelloUI does not download it automatically.
Install it using one of these methods:
yt-dlp.exe from the official releases page, then place it in jello-ui/music/ inside your Minecraft instance directory.winget install yt-dlp.yt-dlp.brew install yt-dlp.yt-dlp package through your distribution's package manager.Alternatively, install yt-dlp on your system PATH.
If YouTube blocks playback with a bot-verification message, place an exported Netscape-format cookies.txt file in jello-ui/music/. JelloUI will pass it to yt-dlp for playback authentication.

ViaFabricPlus 4.6.0 or newer is recommended.
The public API is documented at public API docs. Addons implement JelloAddonInitializer and declare the jelloui:addon Fabric entrypoint.