JustEnoughItems functions as both a server-side and a client-side mod. Most mods need to be installed on both the server and the player’s computer to function and for the player to even be able to join the server.

Is not Enough items client side?

Basically, any mod which changes your perspective without changing the mechanics of the world around you is going to be client-side, generally. So mods like REI’s Minimap or Optifine are client-side. NEI is a special deal because it can be configured server-side to prohibit non-admins from accessing Cheat Mode.

However, mods are a bit more complex than plugins as they can be client-side only, server-side only, or both, depending on the mod. Client-side only means that the mod is to be installed on each player’s Minecraft client, as opposed to the Minecraft server.

Is Neat client side?

Neat is a mod that adds Unit Frames to the top of every entity. That image is a good example of it. Features: Fully client sided.

Using JEI. JEI’s search box can be seen from (almost) any GUI in the bottom right of the screen. Hovering over an item and pressing the “R” key (for Recipe) will display that item’s recipe while pressing the “U” key (for Use) shows what that item can be used to create through crafting grids.