Still works for any version of jellyfin 10.11.x, and also for the most recent versions of file transformation, however all work has been moved to Jellyframe

Mod Manager

A Jellyfin plugin that lets you browse and enable community JS and CSS mods from the server dashboard. Mods are injected at request time — your Jellyfin install is never modified on disk. Multiple mods can be active simultaneously.

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Requirements

• Jellyfin 10.11+
• File Transformation plugin

Both plugins are available from the repository below.

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Installation

1. Add the plugin repository

In Jellyfin, go to Dashboard > Plugins > Repositories and add:

https://raw.githubusercontent.com/Jellyfin-PG/Repository/refs/heads/main/manifest.json

2. Install the plugins

Go to the Catalogue tab. Install File Transformation first, then Mod Manager. Restart Jellyfin after each install, or restart once after both.

3. Open the mod store

Navigate to Dashboard > Mod Manager in the sidebar. Enter a mod repository URL and click Load Mods. Enable whichever mods you want, then click Save & Apply and hard-refresh your browser (Ctrl+Shift+R).

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Mod Repository

The default mod list is loaded from:

https://raw.githubusercontent.com/Jellyfin-PG/Mod-Manager-Mods/main/mods.json

This file is fetched live when you click Load Mods, so new community submissions appear without a plugin update. You can point the URL at any compatible mods.json file, including your own.

To submit a mod, open an issue using the Mod Submission template in the mod repository.

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Mod Format

Each entry in mods.json uses the following structure:

{
  "id": "my-mod",
  "name": "My Mod",
  "author": "author",
  "description": "What the mod does.",
  "version": "1.0.0",
  "type": "js",
  "jellyfin": "10.11+",
  "tags": ["ui", "player"],
  "previewUrl": "",
  "sourceUrl": "https://github.com/author/my-mod",
  "jsUrl": "https://raw.githubusercontent.com/author/my-mod/main/mod.js",
  "jsInline": null,
  "cssUrl": null,
  "cssInline": null
}

The type field accepts "js", "css", or "both". For "both", all four URL/inline fields are supported simultaneously.

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How it works

On every request for index.html, the File Transformation plugin invokes a callback in Mod Manager. The callback reads the list of enabled mods from the plugin configuration and injects the appropriate tags before </body>:

• CSS mods are injected as <style>@import url("...");</style> tags, matching the same approach used by Skin Manager.
• JS mods are fetched at runtime via a small inline loader script and injected as <script> tags with their content set directly, avoiding CORB restrictions.

The original files on disk are never modified. Disabling all mods clears the injection on the next page load.

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License

GPL-3.0