Cartographer for Repixture
Hugues Ross

Adds regional maps that you can craft and place (Repixture version)

Direction Compass
APercy

Adds a compass

rcsv
Wuzzy

RFC-4180-compliant CSV parser and writer

Chatcommand Library
LMD

Library for registering chatcommands.

My Torches
Don

Changes default torches to ones that burn out and cause damage

Nitro Digger
nri

Adds a tool that removes nodes quickly.

Breadcrumbs
FaceDeer

Path marker signs for use when exploring a twisty maze of passages that are all alike.

No Melterns, no tools
InfiniteCoder01

You can't craft tools without melters now. Progression becomes harder

Darks
_Xenon

Adds dark stuff

Database Manager
AFCM

Database Manager API

One death
SFENCE

This allows players to die only once. The world can be destroyed after it (default for single-player) or the player can lose privileges to interact with the world and others (default for multi-player)

Touch
Skamiz Kazzarch

Orient yourself in the darkness by touch.

Some kind of star ... trek, nodes
Paul Wilde

A bunch of nodes you may find on some kind of star trek

Nightandday
sofar

Allows you to have different day and night speeds.

After Earth
AiTechEye

The earth's ecosystem has collapsed, and there are no biologically environment left.

Exchange
Goops

Inject currency into a server economy

Level API
Hypernoot

A library for games to load levels defined as schematics

Renewable Fireflies
mecha_moonboy

Registers an ABM on some ground blocks that spawn fireflies if certain criteria are met.

Register, Attach & Detach
mzel1982

Register glowing 3D items and custom display nodes that you can easily attach to players, place on walls, or showcase on pedestals.

YALib
hutzdog

Yet Another Library

Fake Solids
Holly Mae

Creates fake blocks that can be walked through.

Beamer
Clyde

Beam items or nodes from your inventory to the inventory of your friend.

Sticks Stones
MikeRedwood

Makes Sticks from leaves and scatters small stones

HopCheat
Warr1024

Cheat commands for ColourHop

item_monoids
fluxionary

an API for controlling item properties via monoids

My Stacks
Don

Changes the max number of items in each stack

QR Code
Miniontoby

Create QR Codes in your world

Compression Lib
The4spaceconstants

A library that provides functions to procedurally register compressed versions of nodes.

Matterbridge Player Events
cj_clippy

Sends a message to the matterbridge when a player joins/parts

Playerfactions
mt-mods

A simple mod which allows player created factions. Not very useful on its own, it becomes very powerful when combined with other mods.

Detailed Features
Holly Mae

Lets you see detailed info on specific mods

Simple Materials
Fruitsnack

Modpack providing shared resources for other mods

DataMiner
sorcerykid

DataMiner is an analytical tool for server operators with a feature-rich API for customized report generation

Grow Dry Grass
Silver Sandstone

Makes dry grass spread on savanna dirt.

Global Market
AFCM

Market command

NameGen
cronvel

Name generator API.

Wield Events
mt-mods

Events for wield item switching

Spawn redo
cathaya7d4

Drop-in replacement for default/spawn for more third-party biomes

Natural slopes for Hades Revisited
karamel

Add natural slopes for Hades Revisited

Splink Storage
Yoreni

Adds items that can store massive amounts of other items in your inventory