TopoJSON Splitter

Split TopoJSON topology files into multiple separate files by object or property, while preserving the efficient arc topology structure.

Input TopoJSON

or drag & drop

How to Use

1. Upload TopoJSON file or paste data
2. Choose split method:
   • By object (e.g., countries, states, cities)
   • By property within objects (e.g., country code, admin level)
3. Preview split — See resulting file structure
4. Download all files as ZIP

Features

✓ Split by object — Separate each TopoJSON object into its own file ✓ Split by property — Group features by property value ✓ Preserve topology — Maintains arc sharing and compression ✓ Smart re-topology — Rebuilds arc references for each split ✓ Property detection — Auto-detects available properties ✓ Batch download — Get all files as ZIP archive

Use Cases

🗺️ Extract countries — Split world topology into individual country files 🏛️ Separate layers — Extract different object types (boundaries, rivers, roads) 📊 Regional datasets — Create topology files for specific regions 🎯 Reduce file size — Split large topologies into manageable pieces 🔍 Targeted analysis — Work with specific geographic areas

TopoJSON Structure

TopoJSON files contain multiple named objects:

{
  "type": "Topology",
  "objects": {
    "countries": { ... },
    "states": { ... },
    "cities": { ... }
  },
  "arcs": [ ... ]
}

Split Methods

1. Split by Object

Creates one file per object in the topology.

Example Input:

{
  "objects": {
    "countries": { ... },
    "states": { ... }
  }
}

Output:

• countries.topojson
• states.topojson

2. Split by Property

Splits features within an object by property value.

Example: Split countries object by ISO code Output: One file per country

Tips

💡 Use object split for different layer types (countries, rivers, etc.) 💡 Use property split for extracting individual features 💡 Preview topology to understand arc count and file sizes 💡 Maintain arc efficiency by keeping related features together 💡 Check quantization — Topology precision may affect splits

Technical Details

Input Format

• Valid TopoJSON Topology
• Must contain objects and arcs
• Supports all geometry types

Output Format

• Individual TopoJSON files with reconstructed topology
• Shared arcs are duplicated in each output file
• ZIP archive containing all files

Arc Handling

• Arcs referenced by features are included in output
• Unreferenced arcs are removed
• Arc indices are recomputed for each file

Limitations

• Splitting breaks shared topology (arcs duplicated)
• File size may increase after splitting
• Large topologies may take time to process

Related Tools

• GeoJSON Splitter — Split GeoJSON files
• TopoJSON Merger — Merge TopoJSON files
• GeoJSON ↔ TopoJSON — Convert formats

Frequently Asked Questions

Q: Will splitting increase file size? A: Yes, because shared arcs are duplicated across files. The topology efficiency is partially lost.

Q: Can I split a single object by property? A: Yes! Select the object, then choose property split method.

Q: What happens to shared arcs between features? A: Arcs are duplicated in each output file that needs them.

Q: How do filenames work? A: For object split: object name. For property split: property value (sanitized).

Q: Can I merge the split files back together? A: Yes, use the TopoJSON Merger, but note that shared topology won't be automatically restored.

Q: What if features don't have the split property? A: They're grouped into an "undefined.topojson" file.

Q: Does this preserve quantization and transforms? A: Yes, all topology parameters are preserved in output files.

Q: Can I split very large topology files? A: Yes, but processing time increases with arc count. Files >50MB may be slow.