Useful

Adds a mod menu to view the list of mods you have installed.

A working voice chat in Minecraft!

Shows information about what you are looking at. (Hwyla/Waila fork for Minecraft 1.16+)

Adds dynamic lights to Minecraft as the most feature-complete and optimized dynamic lighting mod.

Adds a search bar to the Key-Bindings menu

A featureful and accessible item and recipe viewer

Vanilla+ additions: Jars, signposts, faucets, weather vanes spring launchers, sconces, planters, lights, decoration and automation

Open a LAN server to anyone, anywhere, anytime.

spark is a performance profiler for Minecraft clients, servers and proxies.

Take insanely large screenshots because why not

Lets you see if players are typing, in a GUI, idle, with cool ingame visuals

Fusion allows resource packs to use additional texture and model types such as connected textures!

Allows players to temporarily mark locations and entities

Xaero WorldMap / Minimap Extra Features

A vanilla and add-on friendly, open-source mod that adds in more tiers of Netherite!

Help your friends back up after they die (if you can make it in time)

Changes the default server compatibility check to compare modpack versions

Adds a draggable trash slot to all inventory screens. Press T to toggle.

Storage mod with multiple tiers and functional upgrades

Never lose your items again!

A proximity voice chat mod with audio positioning and lots of features

Spyglass Improvements is a mod that add various functionality and improvements to the vanilla minecraft spyglass.

Expertly edit your books with rich formatting options, page utilities and more!

A permissions plugin/mod for Minecraft servers.

This little mod allows you to directly equip your Curios items to the respective slots

Brings the sanity mechanic from Don't Starve into Minecraft

Adds a fitting and difficult temperature system to Minecraft, plus more!

A modern take on thirst, compatible with Create, Farmer's Delight & more.

Via Romana introduces a fast travel system where players can link signs over paths, allowing for instant teleportation between them.

Remove that delay when blocking

A vanilla-friendly mini-map/world-map mod using vanilla Maps!

Take high-quality screenshots on Forge

Add bubbles above players heads when they send a message in the chat.

WorldTools is a powerful Minecraft mod that allows you to capture and save high-detail snapshots of server worlds locally.

A mod which substantially improves Minecraft's data driven world generation error detection, reporting, and recovery mechanisms.

A client-side mod that logs exceptions that stop you from joining a server

Overhauls the game's 14 year old text formatting syntax.