Jade

Jade shows information about what the player is looking at. They point the crosshair at a block and immediately see what it is; for a chest, its contents; for a furnace, what is being smelted in it; for a machine from another mod, what it is currently doing. It is not a window that needs to be opened — the information appears by itself at the top of the screen.

It is the successor to the well-known WAILA from the days of 1.12.2 and today it is among the most used mods of all. On technical servers it is almost mandatory: without it, a player at a machine cannot tell whether it is working or stuck.

Jade works in the client — the player installs it on their computer. But if you also install it on the server, the player gets more information (the server sends them data they otherwise would not have). On a modded server, it therefore pays off to have Jade on both sides; players who do not install it lose nothing, they just see less.

Watch out for one thing: Jade also reveals what a player would otherwise not see — the contents of other people's chests or the state of other people's machines. If you deal with privacy on the server (locked chests, secret stashes), go through the settings and decide what Jade should show. Most modpacks already have sensible defaults, but it is good to know that it can be influenced.

For a server, its main benefit is that it reduces the number of questions like “what is this block” — players can figure it out themselves.

1. Jade works in the client; it is optional on the server, but on modded servers it is worth having it on both sides.
2. For the player: install Fabric Loader (or NeoForge) for your game version.
3. Download Jade from modrinth.com/mod/jade in the version for your game version and loader.
4. Upload the .jar to the mods folder (on Windows %appdata%\.minecraft\mods).
5. Start the game and point the crosshair at a block — information must appear at the top of the screen.
6. Open Jade settings (via the mod list or with the keybind from the controls settings) and go through what should be displayed.
7. On the server: upload the same version of Jade to the mods folder and start the server. Verify that it loaded without error.
8. Test for yourself that after installing it on the server you see more information than before (for example, machine status).
9. Go through the privacy settings: should Jade show the contents of other people's chests and the status of other people's machines? Make that decision consciously.
10. Tell your players which version of Jade to use — version mismatches cause the most problems on modded servers.
11. If Jade reports a missing dependency after installation, install Fabric API as well — on Fabric, many mods need it.

Jade works even client-side only. Installing it on the server adds information, but it isn't required — if you skip it, players won't lose the mod.
It displays the contents of other players' chests and the state of other players' machines. Go through the settings and decide what the server should show — with private matters, this can be sensitive.
The Jade versions on players and on the server should be the same. A mismatch will show up as missing or strange information.
If information isn't displaying, verify that the mod is running (it's in the mod list) and that the player has the display configured — someone may have accidentally turned it off in the controls settings.
On technical servers, Jade is almost mandatory — without it, players at machines can't tell what's happening. Recommend it in the rules or on the website.
The mod is free, but the license doesn't allow further distribution — don't download it from other websites, only from Modrinth.