🌐 GeoCRS Transformer

Reproject coordinates between 326 EPSG systems — instantly, in your browser.

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✨ Features

• 326 EPSG coordinate systems — geographic and projected, covering every region of the world
• Manual mode — transform a single coordinate pair interactively
• Batch mode — upload a CSV or Excel file and transform thousands of rows at once
• Angular format support — Decimal Degrees (DD), Degrees Minutes Seconds (DMS), Degrees Decimal Minutes (DMD), and Gradians
• Unit conversions — meters, feet, US survey feet, kilometers, miles
• Per-row CRS — in batch mode, each row can have its own input EPSG code from a dedicated column
• EPSG.io fallback — if a CRS is not in the local database, the tool fetches its proj4 definition from epsg.io automatically
• Zero server required — everything runs in the browser; no data is ever sent anywhere
• Works offline — once loaded, the page and its CRS database function without a network connection

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🚀 Quick Start

Open the live app directly — no installation needed:

https://geoharkat.github.io/GeoCRS_Transformer/

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🗂️ Repository Structure

GeoCRS_Transformer/
├── geocrs_transformer.html   # Single-file application
├── crs_database.js           # 326 EPSG definitions (proj4 strings, wrapped as JS)
└── README.md

The entire UI, logic, and styling lives in geocrs_transformer.html.
crs_database.js is loaded via a <script> tag so the tool works from file:// without a local server.

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🖥️ Manual Mode

Transform one coordinate at a time.

1. Select a region → country → EPSG system for the input CRS
2. Enter X / Longitude / Easting and Y / Latitude / Northing
3. Choose the input angular format (DD, DMS, DMD, Grad, or Auto-Detect)
4. Select the output CRS and desired output format / units
5. Click Transform Coordinate

Use the ⇄ swap button to instantly reverse the input and output systems.

Accepted input formats

Format	Example
Decimal Degrees	30.54
Degrees Minutes Seconds	30° 32' 24" or 30 32 24
Degrees Decimal Minutes	30° 32.4'
Gradians	33.933
With hemisphere letter	30.54N, 6.35E

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📂 Batch Mode

Transform an entire dataset in one step.

1. Drop or select a CSV or Excel (.xlsx / .xls) file
2. Map the X column, Y column, and either:
   • Set a global input CRS (all rows use the same system), or
   • Point to an EPSG column to use a different input CRS per row
3. Choose the output CRS and output format
4. Click Transform & Prepare Download
5. Download the result as a CSV with Out_X and Out_Y columns appended

Example input CSV

X,Y,EPSG
648235.9,6862268,2154
530268.1,179643.9,27700
475762.7,4202404,2100

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🔧 Running Locally

Because the CRS database is loaded via a <script> tag (not fetch), the tool works directly from the filesystem:

# Clone the repo
git clone https://github.com/geoharkat/GeoCRS_Transformer.git
cd GeoCRS_Transformer

# Open directly in your browser — no server needed
open geocrs_transformer.html      # macOS
xdg-open geocrs_transformer.html  # Linux
start geocrs_transformer.html     # Windows

Alternatively, serve it with any static server:

python3 -m http.server 8000
# then open http://localhost:8000/geocrs_transformer.html

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🧰 Tech Stack

Library	Version	Purpose
proj4js	2.9.2	Coordinate reprojection engine
PapaParse	5.4.1	CSV parsing
SheetJS (xlsx)	0.18.5	Excel file parsing
Tailwind CSS	CDN	Utility-first styling
Font Awesome	6.5.1	Icons
Space Grotesk	—	Typography

No build step. No framework. No backend.

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🌍 EPSG Database

The bundled crs_database.js contains 326 EPSG coordinate systems covering:

• Geographic CRS (latitude/longitude in DD, DMS, DMD, or Grad)
• Projected CRS (UTM zones, national grids, Lambert, Mercator, etc.)
• All major regions: Africa, Europe, Americas, Asia-Pacific, Middle East, and more

For any EPSG code not included, the tool automatically falls back to fetching the definition from epsg.io.

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📝 Known Limitations

• Vertical datums are not handled — only horizontal (2D) reprojection is supported.
• Grid-shift transformations (NTv2, NADCON, etc.) are not available in the browser build of proj4js; datum shifts use 7-parameter Helmert transformations only.
• The EPSG.io fallback requires an internet connection.

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🤝 Contributing

Issues and pull requests are welcome. If a CRS is missing from the database or a transformation gives unexpected results, please open an issue with:

• The input EPSG code and coordinate
• The output EPSG code
• The expected vs. actual result

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👤 Author

Ismail Harkat
📧 geoharkat@gmail.com
🌐 geoharkat.github.io/GeoCRS_Transformer

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📄 License

This project is licensed under the MIT License — see the LICENSE file for details.