Stopwatch
sorcerykid

Stopwatch is Lua-based benchmarking API for Minetest developers

Library Mount
Panquesito7

API Framework for mounting objects.

Riddance
Blockhead

Hide or rid yourself of unnecessary items from games and mods without any code

DeltaTime
SkyBuilder1717

Adds deltatime API

craftsystem
fluxionary

craft registration API which automatically deals w/ replacements

Ambience API
1F616EMO

API for playing background musics

Basic HUD textures
Wuzzy

Adds basic but neccessary HUD images: Heart icon, bubble icon, … (for game authors)

Minetest Systemd (API)
Piezo_

Debugging utility and compatibility tools for server owners and/or modpack creators

player actions
GigaByte

shows the actions of a player

Test Harness
IRI

Provides an automated testing framework by simulating player behavior on a server. It allows developers to create, register, and run tests to their packages

Benchmark Engine
theFox

Engine for running benchmarks ingame.

Glob Patterns
1F616EMO

Use glob patterns in Lua and in serveral commands

Wishful
mt-mods

Fully CC0 Base Game