Mods
Fabric API
by modmuss50Lightweight and modular API providing common hooks and intercompatibility measures utilized by mods using the Fabric toolchain.

Sodium
by jellysquid3A high-performance rendering engine replacement for Minecraft, which greatly improves frame rates and reduces micro-stutter.

Iris Shaders
by coderbotA modern shader pack loader for Minecraft intended to be compatible with existing OptiFine shader packs

Entity Culling
by tr7zwUsing async path-tracing to hide Block-/Entities that are not visible

Cloth Config API
by shedanielConfiguration Library for Minecraft Mods

FerriteCore
by malte0811Memory usage optimizations

Mod Menu
by ProspectorAdds a mod menu to view the list of mods you have installed.

Lithium
by jellysquid3No-compromises game logic optimization mod, useful for both single-player games and multi-player servers.

ImmediatelyFast
by RaphiMCSpeed up immediate mode rendering in Minecraft

YetAnotherConfigLib (YACL)
by isxanderA builder-based configuration library for Minecraft!

Fabric Language Kotlin
by modmuss50This is a mod that enables usage of the Kotlin programming language for Fabric mods.

Xaero's Minimap
by thexaeroDisplays a map of the nearby world terrain, players, mobs, entities in the corner of your screen. Lets you create waypoints which help you find the locations you've marked.

[ETF] Entity Texture Features
by TrabenEmissive, Random & Custom texture support for entities in resourcepacks just like Optifine but for Fabric

Architectury API
by shedanielAn intermediary api aimed to ease developing multiplatform mods.

Sodium Extra
by FlashyReeseA Sodium addon that adds features that shouldn't be in Sodium.

Xaero's World Map
by thexaeroAdds a full screen world map which shows you what you have explored in the world. Works great together with Xaero's Minimap.

[EMF] Entity Model Features
by TrabenEMF is an, OptiFine format, Custom Entity Model replacement mod available for Fabric and Forge.

VeinMiner
by MiraculixxMine the whole vein on mining a single ore/block. Make the tedious mining experience to something satisfying and fun! FTB Ultimine alternative
AppleSkin
by squeek502Food/hunger-related HUD improvements

Not Enough Animations
by tr7zwBringing first-person animations to the third-person
Reese's Sodium Options
by FlashyReeseAlternative Options Menu for Sodium

Just Enough Items (JEI)
by mezzView Items and Recipes

3D Skin Layers
by tr7zwRender the player skin layer in 3d!

ModernFix
by embeddedtAll-in-one mod that improves performance, reduces memory usage, and fixes many bugs. Compatible with all your favorite performance mods!