View and edit your Minecraft world in the World tab

The World tab shows your world as a map of regions and lets you open any chunk in 3D. You can break and place blocks, follow players, and delete chunks so the game builds them again. With the server stopped, the panel stages your block changes and writes them to the world files when you save them. With the server running, each change goes through the game. Take a backup before you edit anything.

The tab is on every Minecraft Java server. A new server has no world until it has started once: the page says “This server has no world yet. Start it once and the game creates one.”

Look around

Open the World tab. The line under the title tells you the state: “Running: changes go through the game”, “Stopped: changes are saved to the world files”, or “Starting or stopping: changes wait until it has finished”. It also shows the Minecraft version.
Choose Overworld, Nether or The End (1) above the map. The page shows “REGIONS” with how many the dimension has.
The map (2) is of one region, named by its x and z. It has two views, Surface and Activity. Activity is brighter where players spent more time, up to ten hours or more, and dark chunks were generated but never lingered in.
Point at the map to find a place, and click a chunk to open it in 3D. Chunks nobody has visited say “nobody has been here yet”.
In the 3D view, the arrow keys turn the view and plus and minus zoom. View from has N, E, S, W, Top and Reset. A slider cuts the chunk at a height so you can see inside. Chunks in view (4) shows 1x1 up to 10x10 chunks at once.
Use X, Z and Go to to jump to block coordinates. Players who are online appear on the map, and Follow keeps the view on one of them.

The World tab with the dimension buttons, the region map and a chunk open in 3D with its tools — Overworld, Nether, The End
Region map
Look, Break, Place, Pick, Lasso
Chunks in view

Change blocks

The Look (V), Break (B), Place (P), Pick (I) and Lasso (L) tools sit above the 3D view (3), and the letters are their keys. Break and Place are off if your role cannot edit the world. The page then says “You can look but not change this world.”

Break: click a block to remove it.
Place: choose a block under “Block to place”, then click the face of a block. Pick (or Shift+click) copies a block from the chunk with its facing.
Lasso: drag around blocks to select them. Shift adds, Alt removes. Then Break them, or fill them. The fill block comes from Block to place, and the button reads Fill with plus that block’s name.

For example, to fix a hole in the ground: choose the block in Block to place, choose Lasso, drag around the hole, choose Fill with that block, then save (stopped server: Save with the count; running server: Save now).

While the server is running

Each change goes straight to the running game and counts only when the game confirms it. The view shows the world as last saved plus your changes. The game must have the chunk loaded. If nobody is near it, the panel says so: go there in game, or stop the server.

The Live switch in the side panel shows players every second or two, with blocks as last saved. It follows the game closely and asks it to save while someone is in view, which costs the server a little work, so the panel asks you to confirm. Save now makes the game write the world.

While the server is stopped

The panel stages your changes and draws them in the view. Check them in Changes to save, then choose Save with the count. Use Undo or Discard to drop them. The panel keeps a copy of the region file beside the original before it writes, and tells you the copy’s name when it saves. To go back, stop the server and restore the copy in Files.

Other things the tab does

Select chunks, then Delete: the game builds them again, fresh, the next time a player is near. Everything built in them is gone, and it needs the server stopped. The panel keeps a copy of the region file.
Select by activity picks chunks players barely visited. Find and replace counts one block in the chunks you chose and replaces it, with the server stopped.
Data shows the chunk exactly as the game stored it, and Files the world’s .dat files, such as level.dat. Both are editable only while the server is stopped.
Rules lists every game rule by name and id, each with a switch or a value. A change goes through the game and counts when the game confirms it. For example, Pvp (pvp) is on a new world. See turn PvP on or off.

The Rules tab of the World tab, showing the Pvp rule with its switch on — Pvp switch

By hand

Operators can change blocks in game with /setblock and /fill, which the running game applies at once. Region files sit under world/dimensions/minecraft/<dimension>/region on 26.x, and you can open them in Files if you need to restore a copy.

If it does not work

Break and Place are greyed out. You may lack permission to edit the world, or the server is starting or stopping. The state line under the title says which.
“The game has not loaded that chunk”. Nobody is near it. Go there in game, or stop the server and edit the file instead.
“This chunk could not be read”. The file for that chunk is damaged. Restore a backup of the world.
The map is empty. The world has not been generated. Start the server once.