WorldLedger

Save the parts of a multiplayer Minecraft server you actually explored, and open them later as a single-player world.

A client-only Fabric mod for Minecraft 26.2, plus a command-line tool. Apache-2.0.

How it is different from a world downloader

A world downloader keeps one snapshot of what a player could see and overwrites it the next time. WorldLedger keeps every observation along with the moment it was made and the person who made it.

• Time. An archive can be read at a chosen point in time, not only at its most recent state.
• More than one explorer. Two players who visited the same server can merge what they saw. When their recordings disagree, both are kept and labelled rather than one silently winning.
• Honest gaps. A chunk nobody observed is left out of the exported world, not filled with air. Missing is recorded as missing.

What it does

• Records chunks, biomes and block entities as an ordinary Minecraft client receives them, on a background thread, into a crash-safe folder.
• Imports those recordings into a content-addressed archive where nothing is ever overwritten.
• Writes Anvil region files that an unmodified Minecraft client opens.
• Converts an archive toward an older release, into a separate world, with the losses declared rather than hidden.
• Signs contributions, withholds or removes them on request, and lets two archives merge over a plain folder with no server in between.

Using it

worldledger init ./archive
worldledger ingest-bundle --archive ./archive ./spool/ready-session-sequence
worldledger export --archive ./archive --server example.org --into /path/to/world

The mod writes its recordings while you play; the tool assembles them afterwards. The export is written into a world the game itself created, because the world file that records the version and generator is not something this project should invent.

Where it stands

Rebuilding has been checked in a real Minecraft 26.2 client: an exported chunk loads and renders correctly, including sections below y=0 and block state properties, confirmed both in game and by an independently written reader of the file format.

Builds are pre-releases. One check the project considers necessary has not been done: the same world state captured on two different platforms has never been compared digest for digest. Every claim and its evidence is listed in status.md, including what is not verified.

Before you use it

This records data a normal client receives, on servers whose operators and players may not know an archive exists. Accumulated coverage of a server can reveal more than any single recording does, which is why the tool requires an explicit, attributed decision before it will build anything shareable. The reasoning is in the trust model.

Technical ability to perform an operation is not permission to perform it. Responsibility for use rests with the user, including complying with the terms of any server involved.