Documentation
Meld is a desktop app that puts the real world in Minecraft, from a city block to a whole continent: draw a rectangle on the map, press Generate, and open the result as an ordinary Java Edition world.
Quickstart
Meld is a standalone app. No installer, nothing to uninstall: deleting the folder removes it.
- Download the archive for your operating system.
- Extract it anywhere.
- Run Meld. The builds are unsigned, so the first launch asks once:
- Windows: SmartScreen appears. Click More info, then Run anyway.
- macOS: right-click the app and choose Open, then Open Anyway (or allow it under System Settings, Privacy & Security).
- Draw a rectangle on the map, or search a place.
- Press Generate world. Meld picks the origin, locks the elevation, tiles the selection into cells, and builds them in parallel.
- Copy the world folder into your Minecraft
savesfolder, or use the built-in Server setup to run it as a server right away.
Meld keeps itself current: it notices new releases, downloads and verifies them, and switches over only after the new version has proven it starts, keeping the old one as a rollback. More in The desktop app.
How a build flows, end to end
You draw an area on the map. Meld does the rest in a few clear steps:
- It picks an origin, one fixed anchor that every block coordinate is measured from.
- It runs a quick elevation survey and locks one height range, so the land lines up everywhere.
- It splits the area into cells that fall on region file boundaries, so seams land in clean spots.
- It downloads the area's map data once and shares it to every cell, so nothing gets rate limited.
- It builds many cells in parallel with the Arnis fork, all using the same origin, seed, and height lock.
- It merges each finished cell into one master world, keeping only the part each cell owns.
- A drift guard refuses any cell that does not line up, so a built world is never corrupted.
The result is one Minecraft world with no cliffs and no seams. The guides below explain each piece.
The guides
Each page explains the why, the mechanism, and how to use it in the app.
Start here
The desktop app
The portable tray app: download, extract, run. Self-updates with rollback, and the generator keeps itself current too.
Choosing a scale
From 1:1 city blocks to 1:100 continents: what each ratio costs, what changes automatically, and how to pick.
How it works
How Meld works
The full pipeline: origin, the elevation lock, region aligned cells, map prefetch, parallel generation, the region perfect merge, and the drift guard.
Elevation & terrain
The whole elevation system: the global height lock, region data packs you download once, selectable detail with Auto, no-data hole repair, and the height preview.
Parallel generation
Cells and the worker pool, the CPU budget and staggered starts, stream to disk for huge cells, auto retry, and spiral build order.
The Arnis fork
What the custom Arnis fork changes: seam free rendering, road detail modes, caves, props, farmland, offline data, and how it stays current with upstream.
World features
Caves
One toggle carves a full vanilla-style cave system into every cell: caverns, tunnels, rivers, ores, geodes and eight themed cave biomes, seam-safe across tiles.
Region tree packs
A region aware schematic tree pack: 2,271 hand made models across 176 plant communities and 9 realms, placed by location. Created by paleozoey.
Terrain & snow
Vertical exaggeration to make mountains taller without widening the map, and snow modes (off, realistic, peaks, or a fixed height).
Farmlands & crops
Road aligned field parcels, crop plots with growth stages, three land profiles, and chunk scatter that makes open country read as country.
Props & structures
Boats, cranes, excavators, tractors, wind turbines and lighthouses: 36 schematics placed from real map tags, with one toggle.
Build height
Fit the world’s vertical range to the real terrain instead of vanilla’s -64 to 319, and keep every cell of a tiled world on identical geometry.
Data & offline
Offline data packs
Bake a Geofabrik .pbf and download elevation packs once, then generate fully offline with zero rate limits.
Presets
A world’s look as one sharable file. Three tuned presets ship in the box; machine specific settings are stripped on export.
Projects & render queue
The projects gallery, cloning a project with its settings, and the render queue that builds worlds back to back unattended.
Servers & export
One-click server
World to running Leaf server in five confirmed steps, with hash-verified downloads, border plugins pre-staged, and an optional Voxy streamer.
Export formats
Anvil .mca by default, Linear at roughly 4.85x smaller for servers, and the B_Linear converter. What actually compresses and what does not.
Borders & zones
Build real country borders for a server: preview rings on the map, export WorldGuard regions and a ready border.sk Skript, then trim the world.
Help
Looking for what changed between releases? That lives in the changelog. Already know Arnis? Arnis at scale explains what Meld adds in plain terms.
Common questions
What is Meld?
A desktop app that turns a real map selection into one seamless Minecraft world. It tiles the selection into a grid of cells, builds the cells in parallel, and melds them into a single world with the same terrain height and building style everywhere.
How does Meld relate to Arnis?
Arnis converts one OpenStreetMap bounding box into one Minecraft world, and a single run can only go so big. Meld orchestrates a custom Arnis fork, running many instances at once and merging the results, which is how areas bigger than a single run become possible. The Arnis fork covers what the fork changes.
What do I need to run it?
Just the app: it is standalone, with no installer and nothing to uninstall, and portable builds exist for Windows, macOS, and Linux. The worlds it writes are ordinary Java Edition saves, so vanilla clients and servers open them with nothing installed.
How big can I go?
From 1:1 city blocks to 1:100 continents, depending on the ratio you pick. Before generating, Meld prices the memory, disk, and time a selection needs against your actual machine, and refuses with the fix named when something will not fit. Choosing a scale walks the trade-offs.
Does it work offline?
Yes, once the data is local. Bake a region’s OSM extract and download its elevation packs, then every re-render runs fully offline with zero rate limits. Everything runs on your machine; nothing is uploaded anywhere. See Offline data packs.
Is Meld free?
Yes. Meld is free and open source, built on the open source Arnis generator by louis-e. Map data comes from OpenStreetMap contributors.
Run from source
The app is the recommended path. If you would rather run the repo, it needs Python 3.10 or newer; the GitHub README covers the setup.
Enjoying Meld? Star it on GitHub · questions land in the Arnis Discord.