Most of MCA Selector works on thousands of chunks at once. The Chunk Editor is the opposite: a tree editor for the raw NBT data of exactly one chunk — its terrain data, its points of interest and its entities. It is the microscope you reach for when you need to see, or surgically fix, what is actually inside a chunk.
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.
Opening the Chunk Editor
Select exactly one chunk on the map (zoom in to chunk mode first) and open the editor with Ctrl+B. With zero or multiple chunks selected it will not open — that single-chunk restriction is by design, because the editor shows the complete NBT structure of the region, poi and entities data for that one chunk. If your change needs to happen in many chunks at once, that is the NBT Changer’s job, not this editor’s.
What you are looking at
The editor presents the chunk’s data as an expandable NBT tree: named tags holding numbers, strings, lists and nested compounds, including an array editor for the long array values chunk data is full of. You can add, delete and modify tags. Two habits make this safe rather than scary:
- Read before you write. Spend the first session just exploring a chunk from a throwaway world, so the structure is familiar before anything depends on it.
- Change one thing at a time. A single edited value, verified, beats a heroic multi-tag rewrite you cannot bisect when the chunk misbehaves.
Apply: the one place MCA Selector waits for you
Here is the difference that matters most. Deletes, filter operations and the NBT Changer write to disk the moment they run. The Chunk Editor does not: your edits live in the editor until you press Apply, and only then is the modified chunk data saved to disk (discarding the editor without Apply throws the edits away). This cuts both ways:
- It is the one workflow where “I changed it but nothing happened in game” usually means Apply was never pressed — the most common Chunk Editor support question, with the simplest fix.
- It is also a genuine safety net: you can inspect and stage a risky edit, and back out without touching the world — the only place in the tool where that is true. Your backup is still required, because once Apply is pressed, the write is final.
Good uses for the Chunk Editor
- Diagnosing what a chunk actually contains — which
DataVersionit carries, whether a field the filter relies on is present, what its biome palette holds (the background to the biome guide). - One-off repairs: a single corrupted or wrong value in a known chunk.
- Verifying batch work: after an NBT Changer run on a test selection, open one edited chunk here and confirm the field really changed the way you intended, before scaling the run up.
A safe editing session
- Back up the world; rehearse on a copy if the chunk matters.
- Open the world, zoom to chunk mode, click the one chunk, press Ctrl+B.
- Find the tag, make the smallest edit that expresses your change.
- Press Apply.
- Close the tool, open the world in Minecraft, and check the chunk in game — including its neighbours, since chunk borders are where bad edits show first.
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.