MCA JSON

Overview

MCA JSON is a command-line toolkit and TypeScript library for converting and editing Minecraft Java Edition world data. It suits developers and technically minded world owners who want to inspect or change MCA, NBT, or SNBT files; its strongest case is flexible file handling, with meaningful limits around large and custom-compressed chunks.

Key features

The command-line tools convert MCA and NBT files to JSON and back, list chunks, find signs, remove chunks, and read player locations. That range makes MCA JSON useful for targeted maintenance as well as format conversion, but it is a file-oriented toolkit rather than a general-purpose visual world editor.

The TypeScript library offers typed classes and methods for parsing and modifying MCA, NBT, and SNBT data. It can be installed globally or in a project with npm; Deno, Bun, pnpm, and other package managers can also be used. The library is published only as ES modules, can be bundled for browsers, and does not require Node-specific tooling for browser use. For Node.js, it requires version 20 or newer.

Region structure and NBT reading are described as working across versions, with reported attempts spanning Minecraft 1.2.1 through 1.21. It reads zlib, gzip, LZ4, and uncompressed chunks, but saves modified chunks with zlib. Chunks larger than 1 MiB stored in separate .mcc files and chunks using custom compression cannot be read, although they can still be listed and removed. Those constraints matter if a world includes unusually large or nonstandard chunks.

JSON output can become substantial: an example of a mostly untouched region produced about 1 gigabyte. Compact and condensed output options help manage that scale, but conversion may still be impractical where storage or memory is tight.

Pricing

MCA JSON is free, with a free plan at no cost. The plan includes open-source command-line tools and a JavaScript library for MCA/Anvil and NBT files, with no trial or paid tier described. That makes it accessible for occasional file work and development use; the main trade-offs are technical setup and the stated reading limits, not a paid-plan cap.

Platforms

MCA JSON is listed for Linux, macOS, web, and Windows. The web option reflects the library's ability to be bundled for browser environments, while command-line use depends on a compatible runtime; Node.js users need version 20 or newer. It supports Minecraft Java Edition only. Bedrock Edition uses a different format, so Bedrock world owners should choose a tool built for that edition instead.

Who it's for

Choose MCA JSON if you need scriptable conversion, typed JavaScript or TypeScript access, or direct operations such as removing chunks and reading player locations. It is a particularly good fit for developers integrating world-data handling into a project. If you want an interactive editor, work with Bedrock worlds, or depend on reading large external or custom-compressed chunks, its scope is a poor match.

Pros and cons

• Pros: A free command-line and library toolkit covers conversion, inspection, and modification across MCA, NBT, and SNBT.
• Pros: Multiple compression formats and browser bundling support give developers flexibility across file inputs and environments.
• Cons: It supports Java Edition, not Bedrock Edition, excluding Bedrock worlds.
• Cons: Oversized external chunks and custom-compressed chunks cannot be read, which can block full inspection of some regions.
• Cons: JSON can grow to about 1 gigabyte for a mostly untouched region, demanding care with storage and processing capacity.

Alternatives

For a broader directory of options, browse Minecraft World Editors. Choose Chunker if you want a free, open-source alternative; its description identifies it as an internal tool offered publicly. MCA Selector is another free option for Linux, macOS, and Windows. For Bedrock-oriented choices, consider MCBE Inventory Editor, Bedrock NBT Editor, or Bedrock Toolchest; their names indicate their Bedrock focus, unlike MCA JSON's Java-only support.

Minecraft World Trimmer is a free option for Linux, macOS, and Windows, provided as-is with no warranty. biomed is a free MIT-licensed option for Linux, macOS, and Windows. LiveNBTEditor is free MIT-licensed software for Minecraft Java 26.3, with a Windows editor required.

Verdict

MCA JSON is a strong choice for developers and world owners who want free, scriptable control over Java Edition region and NBT data. Its combination of conversion tools and a typed library is the reason to choose it; look elsewhere if you need Bedrock support, a visual editing workflow, or reliable reading of oversized or custom-compressed chunks.