What BCLib Does and Why It Appears in Your Mod List

BCLib as a shared library

BCLib is a library mod: it contains no items, blocks, mobs, or world content of its own. Instead, it bundles common code and utilities that other mods depend on, so those mods do not each have to reimplement the same foundations.

Because of this, you will usually see BCLib in your mod list without ever installing it deliberately. It arrives as a dependency of another mod. Removing it will break the mods that rely on it, so leave it in place.

This also explains the two most common questions. A crash mentioning BCLib is often really a problem in a mod that uses it, or a mismatch between the BCLib build and that mod's expectations. Likewise, "alloying" searches lead here because some dependent mods use BCLib's shared code for their alloying-style mechanics. BCLib itself does not add alloying; the mod that depends on it does.