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MCA JSON

github.com

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Spec score 7.8 #13 of 35 in Minecraft World Editors

What it is

MCA JSON is a command-line toolkit and TypeScript library for handling Minecraft Java Edition region and data files. Its commands convert MCA and NBT data to JSON and back, list chunks, find signs, remove chunks, and inspect player locations. The library supplies typed methods for parsing and changing MCA, NBT, and SNBT data. The maker reports region structure and NBT reading across versions, with files tried from Minecraft 1.2.1 through 1.21. It reads zlib, gzip, LZ4, and uncompressed chunks; changes are saved with zlib. Installation is documented through npm, with Deno, Bun, pnpm, and other package managers also usable. The library can be bundled for browser use, is distributed only as ES modules, and requires Node.js 20 or newer. It supports Java Edition, not Bedrock. Separate .mcc chunks over 1 MiB and chunks using custom compression cannot be read, though they can be listed and removed. A largely untouched region produced about 1 gigabyte of JSON in an example; compact and condensed output options are documented. The software is free.

Spec sheet

Purpose
MCA JSON provides command-line tools and a JavaScript library for converting Minecraft Anvil and NBT files to JSON, converting back, and modifying data.Read 9 Oct 2026 · github.com
Support
For problems with other Minecraft versions, the maker asks users to supply a test MCA file and problem description or submit a pull request.Read 9 Oct 2026 · github.com
Browser support
The library has no Node-specific tooling requirement and can be bundled for browser environments; it is published as ES modules only.Read 9 Oct 2026 · github.com
Compression
The library reads chunks compressed with zlib, gzip, LZ4, or no compression, while modified chunks are saved with zlib.Read 9 Oct 2026 · github.com
Installation
The maker documents global or project installation with npm and says Deno, Bun, pnpm, and other package managers can also be used.Read 9 Oct 2026 · github.com
JSON size
The maker notes that an example mostly untouched region produced about 1 gigabyte of JSON and documents compact and condensed output options.Read 9 Oct 2026 · github.com
Library
The TypeScript library provides typed classes and methods for parsing and modifying MCA files, NBT files, and SNBT strings.Read 9 Oct 2026 · github.com
Minecraft edition
Only Minecraft Java Edition is supported; Bedrock Edition uses a different format.Read 9 Oct 2026 · github.com
Read limitation
Chunks larger than 1 MiB stored in separate .mcc files and chunks using custom compression cannot be read, though they can still be listed and removed.Read 9 Oct 2026 · github.com
Runtime
The library works with Node.js 20 and newer.Read 9 Oct 2026 · github.com
Tools
Its command-line tools convert MCA and NBT to JSON, list chunks, find signs, remove chunks, and read player locations.Read 9 Oct 2026 · github.com
Version coverage
The maker says region structure and NBT reading work across versions and reports trying files from Minecraft 1.2.1 through 1.21.Read 9 Oct 2026 · github.com

Plans and prices

MCA JSON Free Open-source command-line tools and JavaScript library for MCA/Anvil and NBT files Read 9 Oct 2026 · github.com

Every MCA JSON plan and price →

Strong points and limits

Strong points

  • Converts MCA and NBT data to and from JSON.
  • Can list chunks, find signs, and read player locations.
  • Reads zlib, gzip, LZ4, and uncompressed chunks.
  • Region and NBT support spans reported versions 1.2.1–1.21.
  • Free command-line tools and JavaScript library.

Limits

  • Supports Java Edition only, not Bedrock Edition.
  • Cannot read certain separate .mcc chunks over 1 MiB.
  • Custom-compression chunks cannot be read.
  • Example region output reached about 1 gigabyte.

Who it suits

It suits Java Edition Minecraft users who need to inspect, convert, or edit MCA, NBT, or SNBT data through commands or a TypeScript library. Browser bundling is available for developers, while runtime use requires Node.js 20 or newer.

Verdict

MCA JSON covers conversion, inspection, and modification for Java Edition region and data files, with both command-line and library interfaces. Check its chunk-reading limits and JSON output size against the files you plan to handle.

Where Specifiction places it

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