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Overview

Chunker provides a flexible configuration system that allows you to customize world conversions through JSON configuration files. These files can be placed directly in your world folder or specified via command-line arguments.

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Configuration Files

Chunker supports five main configuration files:

Block Mappings

Custom block and item identifier mappings

World Settings

World-level property customization

Pruning

Region selection and world optimization

Converter Settings

Conversion behavior and feature flags

Dimension Mappings

Dimension-to-dimension mappings

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File Naming Convention

All configuration files follow the naming pattern *.chunker.json:
  • block_mappings.chunker.json
  • converter_settings.chunker.json
  • dimension_mappings.chunker.json
  • pruning.chunker.json
  • world_settings.chunker.json
These files are automatically loaded from the input world directory if present, or can be specified via CLI flags.

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Loading Configuration Files

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Automatic Loading

Place configuration files in your world folder (CLI.java:143-244): 
my_world/
├── level.dat
├── block_mappings.chunker.json
├── pruning.chunker.json
├── converter_settings.chunker.json
├── dimension_mappings.chunker.json
└── world_settings.chunker.json
Chunker will automatically detect and load these files during conversion.

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Command-Line Loading

You can also specify configuration files via CLI flags: 
java -jar chunker-cli.jar \
  -i "my_world" \
  -f BEDROCK_1_20_80 \
  -o "output" \
  -m "block_mappings.json" \
  -s "world_settings.json" \
  -p "pruning.json" \
  -c "converter_settings.json" \
  -d "dimension_mappings.json"

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CLI Flags Reference

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-m / --blockMappings
string
Path to a JSON file or inline JSON object containing block mappings (CLI.java:73-77)
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-s / --worldSettings
string
Path to a JSON file or inline JSON object containing world settings (CLI.java:80-84)
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-p / --pruning
string
Path to a JSON file or inline JSON object containing pruning settings (CLI.java:87-91)
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-c / --converterSettings
string
Path to a JSON file or inline JSON object containing converter settings (CLI.java:94-98)
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-d / --dimensionMappings
string
Path to a JSON file or inline JSON object containing dimension mappings (CLI.java:101-105)
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-k / --keepOriginalNBT
boolean
Keep and write original NBT data to output (only works if output format matches input) (CLI.java:108-111)

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Exporting Configuration

The easiest way to generate configuration files is through the Chunker web interface:
  1. Visit chunker.app
  2. Navigate to Advanced Settings → Converter Settings
  3. Configure your desired settings
  4. Export the configuration files
  5. Place them in your world folder or use with CLI flags
You can also generate these files manually following the schemas documented in each configuration page.

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Configuration Priority

When both methods are used, CLI flags take precedence over files in the world folder:
  1. Highest Priority: CLI flag (-m, -s, -p, -c, -d)
  2. Lower Priority: File in world folder (*.chunker.json)
If you specify a configuration via CLI flag, the corresponding file in the world folder will be ignored.

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Error Handling

Chunker validates configuration files during startup (CLI.java:149-269):
  • Invalid JSON: Conversion fails with parse error
  • Missing required fields: Uses default values where applicable
  • Invalid values: Conversion fails with descriptive error message

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Next Steps

Block Mappings

Learn how to create custom block mappings

Converter Settings

Configure conversion behavior

Pruning

Optimize worlds by removing regions

World Settings

Customize world properties

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