GeckoLib is an animation and physics library for Minecraft, which makes it easier to animate modded objects in Minecraft. GeckoLib became common after changes to the Minecraft Animation Engine made it harder to animate things like entities. GeckoLib is available for Minecraft 1.12.2 and 1.15.2 and newer (or 1.16 or more recent for FabricMC and 1.18 or newer for QuiltMC).

Geckolib is a physics engine it supports many advanced features, such as:

3D keyframe animations, concurrent animation support (good for taking advantage of powerful computers, especially with a lot of cores and sockets, as well as with good GPU),
Particle keyframes
Sound keyframes
Event keyframes
And more.
It also has over 30 easings.

An extension-based programming language called Molang, also borrowed from the Bedrock edition, helps with animation.

GeckoLib is used differently for developers and players. For Players, you should install the mod in the mods folder like any other mod. For Developers, you will need to add the mod to your development environment, depending on how your environment is and then start developing.

One of the most important things to keep in mind is the versions of GeckoLib. There are 3 Main versions of GeckoLib you need to look out for in Modern mods:

GeckoLib 2: This version is primarily deprecated, but some mods still use it

GeckoLib 3: This version is still common, especially for versions of Minecraft before 1.19

GeckoLib 4: The newest GeckoLib, 1.19.x and newer only

Only GeckoLib 3 and 4 are still being developed. GeckoLib2 and the original GeckoLib are deprecated and should not be used. GeckoLib 3 is in support mode, may eventually be phased out, and mainly targets older versions. Versions of GeckoLib are not compatible with mods made for other versions, which is why it is vital to install the correct version. The modid often indicates the correct version. It will usually say geckolib3 or geckolib2. Both of these versions of GeckoLib should work together.

Since GeckoLib3 Geckolib uses bedrock-style JSON files for the animations and often tries to avoid animations with java (different than many older ways of doing it), GeckoLib integrates with BlockBench and is the preferred method for it, so if you are using BlockBench, animating will likely be much easier with GeckoLib.

GeckoLib covers not just mobs but other entities, items, blocks, armour, and more.

GeckoLib has wikis for support for GeckoLib 3 and GeckoLib 4. It explains how various topics such as how to make and work with models, how to do the animations, examples of the animations, how to set up GeckoLib with MultiLoader, a list of mods which use GeckoLib, Migration guides from 3 to 3,1 and 3,1,x to 4, renderers, glowing, keyframes, Molang, abstract textures, miscellaneous topics, FAQs, and so much more, it took hours for them to make and it is hosted on their GitHub. https://github.com/bernie-g/geckolib/wiki

GeckoLib is one of the most common animation libraries. It is commonly suggested and commonly used by other mods and templates. Requiring this mod will likely be manageable because many other mods use it. Some of the mod developers who use it also are involved in the development or community, such as MC Doom (AzureDoom is one of the top GeckoLib Developers), Chocolate Quest Repoured (Der Toaster is a contributor), Chaos Awakens, Raid Awakens, Minecraft Forge (Curle the Crook is a contributor), Advent of Ascension (Tsalt is a contributor), Mowzie’s Mobs (Bob Mowzie is a contributor and so many more), Ars Nouveau. Here is a small list of a few of the mods officially supported by the GeckoLib team.

newest

fresh

relevant

playable

legacy

GeckoLib Mod