Architectury API

Architectury API is a library mod created by shedaniel. A cross-platform modding API that allows developers to write mods compatible with both Forge and Fabric from a single codebase. As a library mod it concentrates on shared code that other mods build on, and it has been downloaded around 200 million times, which puts it among the options players reach for in this space.

Architectury API is built for modpack authors and developers, as a required cross-loader library. It lets a single codebase target Fabric, Forge, and NeoForge, which is why many multi-loader mods list it as a dependency rather than a player feature. It is a deep, systems-heavy mod, and getting the most from it means investing real time in its mechanics.

The mod is available for Forge, Fabric, NeoForge, and Quilt, so it fits a range of modpacks and launchers. It currently supports Minecraft 1.20.1, 1.20.4, 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.

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, Architectury API 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 developer library). They overlap in purpose, so most players pick whichever suits their loader and pack.