FTB Library

FTB Library is a library mod created by FTB Team. A shared library for FTB mods providing GUIs, networking, sidebar integration, and team management systems. As a library mod it concentrates on shared code that other mods build on, and it has been downloaded around 60 million times, which puts it among the options players reach for in this space.

FTB Library is built for players installing FTB mods such as FTB Chunks or FTB Quests. FTB Library is the shared base the FTB suite depends on, providing common UI and data systems for those mods. It is approachable enough to drop into a world and use right away, with little setup required.

The mod is available for Forge, Fabric, and NeoForge, so it fits a range of modpacks and launchers. It currently supports Minecraft 1.20.1 and 1.21.1, spanning the 1.20.1 to 1.21.1 releases. It runs on both the client and the server, so on a multiplayer server every player who connects needs it installed alongside the server itself.

FTB Library works particularly well alongside FTB Chunks, FTB Quests, and Architectury API. It depends on Architectury API, so those must be present and on the same loader and version. Because it ships for both Fabric and Forge-family loaders, it slots into most popular modpacks regardless of which side they are built on.

As a library mod, FTB Library adds no content of its own and has a negligible footprint, it exists to support the mods that depend on it.

If you are comparing options, a similar mod worth a look is (no direct alternative, it is a dependency library). They overlap in purpose, so most players pick whichever suits their loader and pack.