CSV Doctor

English · 日本語

A browser-based CSV cleaning and WebGIS conversion tool. Load Shift_JIS / CP932 / UTF-8 CSV files, apply automatic cleaning, and download a clean UTF-8 CSV with no character corruption. If coordinate columns are present, it also converts to GeoJSON / CZML / KML.

All processing happens in your browser. Files are never uploaded to a server.

🚀 Online demo: https://csv-doctor.surreal.tools (coming soon)

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Features

CSV Cleaning

Feature	Description
Auto-detect encoding	Shift_JIS / CP932 / UTF-8 (with/without BOM)
Auto-detect delimiter	Comma / semicolon / tab
Unicode normalization (NFKC)	Converts full-width characters to half-width
Invisible character removal	Strips zero-width spaces and other control characters
Trim header/cell whitespace	Removes leading and trailing whitespace
Multiline cell normalization	Unifies line breaks inside cells
Empty row removal	Deletes rows with no data
Duplicate/empty header handling	Appends suffixes to duplicates, auto-names empty headers

File Limits

Item	Limit
File size	50 MB (error above, warning above 5 MB)
Row count	100,000 rows

Coordinate Column Auto-Detection

• Automatically identifies longitude/latitude columns from CSV headers and pre-fills the export panel dropdowns
• Supports English (longitude, lat, lng, etc.), Chinese (经度, 纬度), and Japanese (経度, 緯度)
• Falls back to manual selection if detection fails

GeoJSON Export

• Select longitude/latitude (required) and height (optional) columns from the UI
• Outputs selected coordinates as Point geometry
• Rows with invalid coordinates are output as geometry: null (rows are not dropped)
• Non-coordinate columns are automatically stored in properties (numeric strings are converted to number)
• Marker color and size specified via UI are output as marker-color / marker-size properties
• Output format: GeoJSON FeatureCollection (application/geo+json)

CZML Export

• Specify longitude/latitude/height columns, name column, point color, and size
• Height defaults to 0 m if unspecified
• Directly usable in Cesium / Re:Earth and other CZML viewers
• Output format: CZML (application/json)

KML Export

• Specify longitude/latitude/height columns, name column, description column, icon color, and scale
• Icon color #RRGGBB is automatically converted to KML's AABBGGRR format
• Directly usable in Google Earth / QGIS and other KML-compatible apps
• Output format: KML (application/vnd.google-earth.kml+xml)

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Tech Stack

Item	Details
Framework	React 19 + TypeScript
Build tool	Vite 8
CSV parser	PapaParse
Encoding conversion	encoding-japanese
Styling	Plain CSS (no framework)

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Project Structure

src/
├── App.tsx                     # Root component & processing pipeline
├── types/
│   └── csv.ts                  # Type definitions (ProcessingResult, GeoJSONExportOptions, etc.)
├── lib/
│   ├── detectEncoding.ts       # Encoding detection
│   ├── decodeFile.ts           # ArrayBuffer → string decoding
│   ├── normalizeText.ts        # Text-level normalization
│   ├── detectDelimiter.ts      # Delimiter detection
│   ├── parseCsv.ts             # CSV parsing (PapaParse wrapper)
│   ├── normalizeHeaders.ts     # Header normalization & dedup
│   ├── normalizeCells.ts       # Cell normalization
│   ├── filterEmptyRows.ts      # Empty row filter
│   ├── validateRows.ts         # Validation & warning generation
│   ├── regenerateCsv.ts        # Clean CSV regeneration
│   ├── generateGeojson.ts      # GeoJSON conversion
│   ├── generateCzml.ts         # CZML conversion
│   └── generateKml.ts          # KML conversion
└── components/
    ├── FileDropzone.tsx        # File drop/select UI
    ├── FileSummary.tsx         # File info summary
    ├── OptionsPanel.tsx        # Cleaning options UI
    ├── CleaningReport.tsx      # Processing results & warnings
    ├── PreviewTable.tsx        # Data preview table
    ├── DownloadButton.tsx      # CSV download button
    ├── GeoJSONPanel.tsx        # GeoJSON export UI
    ├── CZMLPanel.tsx           # CZML export UI
    ├── KMLPanel.tsx            # KML export UI
    └── ErrorNotice.tsx         # Error display

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Development

# Install dependencies
npm install

# Start dev server
npm run dev

# Production build
npm run build

# Preview the build
npm run preview

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Processing Pipeline

File (Shift_JIS / UTF-8)
  └─ detectEncoding       → Encoding detection
  └─ decodeFile           → Decode to UTF-16 string
  └─ normalizeText        → Strip BOM / unify newlines / NFKC / remove invisible chars
  └─ detectDelimiter      → Delimiter detection
  └─ parseCsv             → rows: string[][]
  └─ normalizeHeaders     → Dedup / fill empty headers
  └─ normalizeCells       → Trim / multiline normalization
  └─ filterEmptyRows      → Remove empty rows
  └─ validateRows         → Generate warning list
  └─ regenerateCsv        → Clean UTF-8 CSV text
                          → (optional) generateGeojson → GeoJSON FeatureCollection
                          → (optional) generateCzml    → CZML
                          → (optional) generateKml     → KML

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Built With Claude

This project was built with Claude Code, Anthropic's AI coding assistant, as a pair-programming collaborator across design, implementation, and documentation.

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License

MIT License © 2026 lavalse