How to upload your single-player world to your server

Built something in single-player that you now want to share? You can move the whole world onto your Cobbly server — every build, chest and explored chunk — and play it with friends. This guide covers finding the save, packing it so the server accepts it, uploading it, and taking a world back the other way.

Before you start

• Java Edition worlds only. Bedrock worlds use a different format and cannot run on a Java server.
• Match or exceed the version. The server should run the same Minecraft version the world was last played on, or a newer one. Opening a world on an older version is not supported and can corrupt it. Set the version on the Software tab first.
• Modded worlds need the same mods. A world made with mods only loads correctly on a server with the same loader and mods — otherwise the modded blocks vanish.
• Size limits. The .zip can be up to 2 GB, and the unpacked world has to fit in your 10 GB of storage.
• It replaces the current world. Uploading deletes the world already on the server. If you might want it later, download it first from the World tab.

Step 1: find your save folder

Single-player worlds live in the saves folder inside your Minecraft directory. The quickest way there on any system: in the launcher, open Installations, hover over your installation and press the folder icon, then open saves. Or go directly:

• Windows — press Win + R, type %appdata%\.minecraft\saves and press Enter.
• macOS — in Finder, Go → Go to Folder, and enter ~/Library/Application Support/minecraft/saves.
• Linux — ~/.minecraft/saves.

Each folder in saves is one world, named the way it was when you created it. Quit Minecraft completely before copying anything, so the world is not half-written.

Step 2: rename a copy to "world"

The server looks for a folder called exactly world. Copy your world folder somewhere else — the desktop is fine — and rename the copy to world, all lower-case. Working on a copy means your original single-player save is untouched whatever happens.

Step 3: zip it the right way

Compress the folder itself, not the files inside it. When you open the finished .zip, you should see a single world folder at the top, with level.dat, region and the rest inside that.

• Windows — right-click the world folder → Send to → Compressed (zipped) folder.
• macOS — right-click the world folder → Compress "world".

The most common upload error — "No world/ folder found in that .zip" — means the files were zipped without their folder. Zip the folder again, not its contents.

Step 4: upload it

1. Stop the server.
2. Open the World tab and choose Upload World.
3. Pick your .zip and wait for it to finish. A message tells you how many files were restored.
4. Press Start, then join and look around.

In single-player, the Nether and the End are stored inside the world folder, and they come along automatically. If your server runs Paper or Purpur, it moves them into their own world_nether and world_the_end folders on the first start — that is normal.

After uploading

• Make yourself an operator again with op YourName in the Console tab — operator lists belong to the server, not the world.
• Your single-player inventory is kept only if you join with the same Minecraft account you played it on.
• Game rules and difficulty come with the world. Change them without starting over from World → Level Config.

Taking a world back to your PC

The World tab’s Download World button saves the whole world as a .zip, even while the server is asleep. Unzip it into your saves folder to play it in single-player. If the server runs Paper, the Nether and End come as separate world_nether and world_the_end folders; single-player expects them inside the main world folder, as DIM-1 and DIM1.