Lib99j
by Daniel99j
Lib99j is a server-side library for Fabric and Quilt that gives other mods tools for effects, screens, particles and configuration, and it requires Polymer.
What it does
Lib99j is a server-side library. It provides building blocks for server-side development: GUI textures, particles, camera overlays, hidden boss bars, custom effects and a way to create configuration files. Mods built on Polymer can use these pieces without the client needing the library, and a client-side mod can pair with it where the author text describes a companion role.
The library also includes a tool set for scene and interface work. Its controls can restart a scene, move to the next or previous scene, select and skip steps, open a menu, and show an in-game HUD. A UI creator and a stained glass overlay that marks the safe area help when laying out screens. Polymer must be installed alongside Lib99j, since the mod is built on it.
Files are published for Fabric and Quilt across six game versions, 1.21.5 – 26.1, and the latest build for both loaders is 1.4.1 for 26.1, released on 2026-03-29. The code is under the MIT License and is open source; the source code and issue tracker are public. It runs on the server alone, so players need nothing extra to join.
Key features
Server-side particles and GUI textures
Particles and GUI textures can be sent from the server, so effects appear without a client-side mod.
Camera overlays and hidden boss bars
Camera overlays can lock the view in a scene, and boss bars can be hidden for chosen players.
Scene controls and UI creator
Scenes can be restarted, advanced, rewound or skipped step by step, with a menu, a HUD and a UI creator for layouts.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Who it’s for: Developers of server-side Polymer mods, and server owners who run scenes or guided content on Fabric and Quilt.
How it compares
Booklet is server-side only, open source under the GNU Lesser General Public License v3.0 only, and published for Fabric on 1.21.11 – 26.3. Cutscene Engine covers Fabric, Forge, NeoForge and Quilt for 1.21.6 – 26.1.2, with the server required and the client optional, under All rights reserved. VFXWeaver API is client required and open source under the MIT License for NeoForge and Fabric on 1.21.11 – 26.2.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Lib99j | Fabric and Quilt | 1.21.5 – 26.1 | Server-side only | 2026-03-29 |
| Booklet | Fabric | 1.21.11 – 26.3 | Server-side only | 2026-09-11 |
| Cutscene Engine | Fabric, Forge, NeoForge and Quilt | 1.21.6 – 26.1.2 | Server required, client optional | 2026-04-22 |
| VFXWeaver API | Fabric and NeoForge | 1.21.11 – 26.2 | Client required, server optional | 2026-10-14 |
Questions
Does Lib99j need Polymer?
Does a player need to install Lib99j?
Which loaders and game versions are supported?
In the catalog
Lib99j is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 11,959 mods support Minecraft 26.1.
Similar mods
What the author says
Features: - No client mods - Skip, rewind, and pause - If installed alongside Polydex or Booklet, click once to open a ponder - Fast - Does not change the player - neither the server or client know you are pondering, everything happens at the network level - Fully self-contained - No real-world changes - Works with…
Official listing
- Modrinth page
- modrinth.com/mod/lib99j
- Owner
- Daniel99j
- Published
- 2025-05-10
- Updated on Modrinth
- 2026-03-29
- Facts verified
- 2026-10-15