Mapsync
BuckarooBanzai

Synchronize the ingame map with a lua-backend

markdown2formspec
Just_Visiting

A markdown to Formspec Utility

Geodes Library
alerikaisattera

API/library for creating geodes

Flow
luk3yx

A formspec library that automatically positions and sizes elements

Geodes
AwesomeDragon97

Adds amethyst geodes and an API for making custom geodes.

Library Mount
Panquesito7

API Framework for mounting objects.

smartshop (flux's fork)
fluxionary

a smarter and easier shop

SzUtilPack
Warr1024

A collection of misc dependency-free utilities primarily for server hosts.

Splooshy Bombs API
ekl

API for block-flinging bombs

futil
fluxionary

flux's utility mod

NucleoTest
LissoBone

Battle Royale-like game. Provides an API and a reference implementation. Highly radioactive. Work in progress.

LootChests Modpack
mt-mods

Modpack adding a lot of various loot containers across the world to be found and providing an API, resources and integrations for other mods

Luamap
MisterE

An easy-to-use api for lua mapgens that takes the pain out of mapgen coding. Focus on mapgen logic, not on voxelmanipulation.

Commodity market
FaceDeer

Provides API support for various in-world commodity markets

Repixture Crafting Compatibility
Silver Sandstone

Converts crafting recipes to be compatible with Repixture.

Skills
giov4

An API for creating skills.

Arena_lib
Zughy

Library working as a core for any mini-game you have in mind

AirUtils
APercy

A lib for airplanes and some useful tools

Player Info
Sumianvoice

Adds a way to track information about the player and controls.

Cycles
1F616EMO

API to cycle though block/item state on certan events

group:any
1F616EMO

Item group applied to ALL items for crafting recipes.

Jean's Economy
Jean3219

Full Economy for Servers like, paying, individual bank statemants, daily rewards, easy api for modders, easy integration with other mods ...

Filled Bottles
EmptyStar

Filled bottles for Minetest Game