World Share

Backup your worlds before use! This is a BETA!

Share one singleplayer world with a friend through a shared drive folder without ever losing progress or mixing up inventories.

Perfect for two friends who take turns on a survival world but can’t (or don’t want to) run a server or pay for Realms.

What it does

On the Singleplayer screen you get three new buttons, and synced worlds show a gold (Shared World) tag:

Upload World: sends the selected world to your shared Drive folder.
Download World: grabs the newest version from Drive (your old copy is backed up locally first).
Drive Worlds: see all shared worlds, who’s playing right now, and download worlds you don’t have yet.

Also comes with built-in save protection!
Live presence: while your friend is in the world, you can’t accidentally play your copy, the mod kicks you back to the menu and suggests joining them instead (e.g. via LAN or Essential). Crash-proof: presence expires automatically after 3 minutes.
Pending uploads: if your friend played but forgot to upload, the mod tells you exactly that and refuses to let the save split in two.
Version tracking: if Drive has a newer version than your copy, you’re told to download before playing.
Player data protection: each of you keeps your OWN inventory, position and XP, the mod fixes the level.dat quirk that normally gives you the other player’s body when opening their world.
Backups: the previous version stays in Drive, and replaced local copies are kept in .minecraft/worldsync-backups (both limits configurable).

Setup (one-time, ~3 minutes, free)
The mod has a built-in, step-by-step Setup Guide (Singleplayer → Drive Worlds → Settings → Setup Guide). Short version:

Make one free account at koofr.eu together (10 GB, no card needed).
Generate an app password on the Koofr site (Preferences → Password → App passwords).
Both players: Settings → Easy cloud setup → enter the e-mail + app password → Test & Save. Done.

Any other WebDAV cloud (e.g. Nextcloud) works too. Prefer Google Drive? There’s an advanced option for that in Settings, the guide covers it.

There is no third-party server and the developer never sees your worlds: everything goes into the cloud account you created.

Requirements
Minecraft with Fabric Loader
Fabric API (required dependency)
(optional) Mod Menu for a settings shortcut
One free cloud account (koofr.eu recommended; Google Drive optional)

FAQ
Is this a server? No, you still play singleplayer, taking turns. For playing at the same time, one of you opens to LAN or uses something like Essential; this mod even suggests that when your friend is online.

More than 2 friends? Works, same oauth-client.json and folder for everyone, each with their own Google sign-in; the mod enforces one player at a time per world.

Do I need a Google account? No, the easy setup uses a free Koofr account. Google Drive is just an optional alternative.

Please report bugs to [email protected]. PLEASE ATTACH LOGS!