Deftera is a server that adds custom items, mobs, and bosses into the game without the requirement of mods. This server is experimental, so if you come across an issue, tell us on the discord server.
If you don’t want custom stuff added, there is also a vanilla world that you can join. There are also two creative worlds if you don’t want to play survival.
A few types of items that are added are guns, knives, gauntlets, and new types of pickaxes, axes, and shovels.
Hope you have fun!
mc.deftera.net