MCA Selector is a free, open-source desktop tool that lets you select chunks and regions in a Minecraft Java Edition world and delete, export or edit them — prune an overgrown world before an update, move a build to another save, reset terrain your players only flew over once. This guide covers the whole workflow end to end: opening a world, reading the map, selecting chunks, and making a first edit you can trust.
Before you start: install it and back up
Grab the current release (2.9) from the download page. Windows users get an installer that bundles its own Java runtime; if you run the cross-platform .jar instead, you need a 64-bit JRE 21 or newer with JavaFX — see the Java requirements guide if the .jar will not start. The tool needs at least 6 GB of RAM available for large worlds.
Back up your world first: MCA Selector writes deletions and NBT changes straight to disk the moment you confirm them — there is no undo and no File → Save step to catch a mistake. Close Minecraft (and stop your server, if the world is on one), then copy the whole world folder somewhere safe before you edit.
Step 1: Open your world folder — the right level matters
Launch MCA Selector and choose File → Open World. In the folder picker, select the world folder itself — the folder that directly contains the region and poi subfolders (for a single-player world, that is the folder with the world’s name inside your saves folder). Picking the saves folder above it, or the region folder inside it, is the classic beginner mistake: the tool then finds no dimensions and shows an empty or error state. If you open a multiplayer server world, open the world folder on the server (with the server stopped) the same way.
Step 2: Read the map — navigation, zoom and overlays
The world renders as a top-down map. Drag to pan and scroll to zoom. Zooming is not just cosmetic: zoomed in, the grid shows individual chunks (16×16 blocks each) and you select chunks; zoomed out, the grid switches to regions (32×32 chunks, 512×512 blocks each) and you select whole regions. Which mode you are in decides what a click selects — and what a deletion removes — so always check the grid before you act. The toolbar also offers overlays that draw extra information on the map, and a height slider that can render the world below a chosen height, which is how you look under the Nether ceiling.
Step 3: Select chunks or regions
Click a chunk to select it, or drag across the map to select a rectangle. Hold Shift to paint a free-form selection with the mouse like a brush. The Selection menu can Invert the selection (everything except what you picked) or Clear it. A selection is the starting point for almost everything else in the tool — the full toolbox is covered in the selection tools guide.
Step 4: Save your selection as a CSV
Selections only exist while the tool is open — unless you save them. Selection → Export selection writes the selection to a CSV file; Selection → Import selection loads it back later, either adding to the current selection (Add Selection) or cutting shapes out of it (Subtraction mode). For any world you care about, export the selection before you run a destructive operation: it documents exactly what you touched and lets you rebuild the same selection on your backup copy.
Step 5: Make a first, safe edit
The safest first edit is an export, because it changes nothing in the original world:
- With Minecraft closed, open a copy of your world (practice on the copy, not the original).
- Select a few chunks that contain a build.
- Choose Selection → Export selected chunks and pick an empty target folder. MCA Selector writes new
region,poiandentitiesfolders there — a portable piece of world you can later import elsewhere. - Close the tool, open the copy in Minecraft, and confirm everything looks as expected.
Once that works, the destructive and editing operations follow the same select-then-apply pattern:
- Delete chunks — remove selected chunks instantly and permanently.
- Reset chunks — delete chunks so Minecraft regenerates fresh terrain.
- Export & import chunks — move pieces of a world into another save.
- Filters — select chunks by DataVersion, InhabitedTime, biome and more instead of by hand.
- NBT Changer — batch-edit chunk data such as biome or DataVersion.
- Chunk Editor — edit one chunk’s raw NBT tree (Ctrl+B), then press Apply.
- Change a biome — set a whole chunk to a single biome via the NBT Changer.
- Prune a world for an update — keep your builds, regenerate everything else.
- Reduce world size — delete dead chunks and defragment region files.
The five beginner pitfalls
- Editing while the world is open. MCA Selector is an external tool. If Minecraft or a server has the world loaded, it can overwrite your edits — or corrupt the save. Always close the world first.
- Expecting a Save button. There is none. Deletes, filter deletes and NBT Changer changes write to disk immediately; only the single-chunk editor waits for you to press Apply.
- Expecting Undo. There is none. Your backup copy is the undo.
- Deleting in the wrong zoom mode. Zoomed out, one click selects a whole region — 1,024 chunks. Check the grid before every deletion.
- Opening a Bedrock world. MCA Selector reads Java Edition Anvil (
.mca) saves only. Bedrock worlds use a different format and cannot be opened — see MCA Selector and Bedrock for your options.
Download MCA Selector 2.9
Everything in this guide works with the current release. Get the Windows installer, the cross-platform .jar, the macOS .dmg or the Linux .deb/.rpm from the MCA Selector download page — every button there points at the official GitHub release files and lists the SHA-256 checksum, with a clearly labelled site mirror as a fallback.
One last backup reminder: keep the copy of your world you made before editing until you have loaded the edited world in Minecraft and confirmed it looks right. Deletions and NBT changes in MCA Selector are permanent once applied.
Related guides
This guide is the hub for the whole tutorial series. Work through the topics in whatever order your project needs: