Introducing DigiPIN.js: India's Coordinate-to-Postal Code Converter for Developers

Why India Needs a Better Location System

As developers, we often deal with messy, inconsistent address data - especially in India. Think of long, ambiguous addresses, missing landmarks, and PIN codes that don’t tell us exactly where someone is.

But what if we had a compact, precise, and standardized way to represent any location in India?

Meet DIGIPIN:

DIGIPIN (Digital Postal Index Number) is a government-backed system that converts GPS coordinates into short, human-readable codes - like:

28.6139°N, 77.2090°E → 39J-438-TJC7

It was developed by:

• Department of Posts, Govt of India

• Indian Institute of Technology, Hyderabad

• National Remote Sensing Centre, ISRO

📦 Introducing digipinjs

To help developers integrate DIGIPIN into real-world apps, I built digipinjs - a full-featured, TypeScript-first library for working with DIGIPIN codes.

🔧 What It Does

• 🔁 Convert coordinates ↔ DIGIPIN

• ⚡ Batch encode/decode

• 🧠 LRU caching for fast repeat lookups

• 🧪 Fully typed, clean API

• 🧵 Built-in CLI tool

• 🌐 Express middleware support

• 🗺️ Grid generation + reverse geocoding

🚀 Quick Start

📥 Installation

npm install digipinjs
# or yarn add digipinjs

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🧪 Usage Examples

1. Use from the CLI

npx digipin-cli encode --lat 28.6139 --lng 77.2090
# Output: 39J-438-TJC7

npx digipin-cli decode --pin 39J-438-TJC7
# Output: Latitude: 28.613901, Longitude: 77.208998

You can even use DMS format or verbose output:

npx digipin-cli encode --lat 28.6139 --lng 77.2090 --verbose --format dms

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2. Programmatic Use

import { getDigiPin, getLatLngFromDigiPin } from 'digipinjs';

const pin = getDigiPin(28.6139, 77.2090);
console.log(pin); // "39J-438-TJC7"

const coords = getLatLngFromDigiPin(pin);
console.log(coords); // { latitude: 28.6139, longitude: 77.2090 }

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3. Batch Processing

const pins = batchEncode([
  { lat: 28.6139, lng: 77.2090 },  // Delhi
  { lat: 19.0760, lng: 72.8777 },  // Mumbai
  { lat: 12.9716, lng: 77.5946 }   // Bangalore
]);

console.log(pins);
// ["39J-438-TJC7", "4FK-595-8823", "2L7-3K9-8P2F"]

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4. Express Middleware Integration

import express from 'express';
import { digiPinMiddleware } from 'digipinjs';

const app = express();
app.use(digiPinMiddleware()); // adds `X-DIGIPIN` header based on coordinates

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🧠 How the DIGIPIN Format Works

DIGIPIN uses a 10-character format split with hyphens:

XXX-XXX-XXXX

It’s generated using a 16-character alphabet optimized for postal use:

Characters: F, C, 9, 8, J, 3, 2, 7, K, 4, 5, 6, L, M, P, T

This encoding ensures:

• ✨ Compactness

• 🧍‍♂️ Human readability

• 📍 Location accuracy

• 🧭 Uniform coverage of the entire Indian subcontinent

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⚠️ Error Handling

try {
  getDigiPin(100, 200); // Out of bounds
} catch (error) {
  console.error(error.message); // "Latitude out of range"
}

Invalid codes are handled cleanly too:

getLatLngFromDigiPin("INVALID");
// throws: "Invalid DIGIPIN"

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🛠️ Dev Tools Included

• npm run build – compile TypeScript

• npm run lint – run ESLint

• npm test – full test suite

• node examples/full-usage-npm.js – example script

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📈 Performance

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👥 Who Should Use This?

• E-commerce devs standardizing delivery coordinates

• Real estate platforms geotagging properties

• GIS/mapping developers

• Emergency response tools

• Indian civic-tech & govtech hackers

• React Native apps with location services

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🤝 Contribute/Collaborate

This project is open source under a dual license:

• Wrapper (digipinjs) - MIT

• Original DIGIPIN algorithm - Apache 2.0

GitHub: https://github.com/rajatguptaa/digipinjs

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🌟 What’s Next?

• 🔲 React-based map UI component

• 🔄 REST API / hosted encode-decode microservice

• 📲 Mobile SDK (React Native)

• 🎓 Blog series on geolocation systems for India

If you’ve got ideas, questions, or want to integrate this in your app - I’d love to hear from you!

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❤️ Made for India’s Developer Community

If you've ever dealt with inconsistent location data in India - digipinjs might save you hours of pain.
Give it a spin, star it, and share feedback - every suggestion counts.

👉 Try it on npm
👉 View the source on GitHub