Geocoder Pro

pub package likes popularity points License: MIT

A powerful, developer-friendly Flutter and Dart package for forward and reverse geocoding. Supports both Google Maps Geocoding API and free OpenStreetMap (Nominatim), spatial distance calculations, compass bearings, geofencing, and typed error handling.

🌟 Highlights & Features

  • 🆓 Free OpenStreetMap (Nominatim) Support — Geocode without needing an API key or credit card.
  • 🌐 Google Maps Geocoding API — Full enterprise Google Maps support with component filtering, bounding boxes, and region biasing.
  • 🔄 Forward & Reverse Geocoding — Convert addresses to geographic coordinates and coordinates back to human-readable addresses.
  • 📑 Multiple Results Support — Fetch lists of matching locations, not just the single top result.
  • 📐 Spatial & Geolocation Utilities (GeoUtils) — Calculate Haversine distances (meters, km, miles), compass bearings, radius geofencing, and DMS coordinate conversions.
  • 🛡️ Typed Exceptions — Clean, predictable error handling (ApiKeyException, QuotaExceededException, NetworkException, NotFoundException).
  • 💎 Modern & Immutable Models — Fully immutable GeoData, GeoCoordinates, and GeoBounds with copyWith, JSON serialization, equality, and hash codes.
  • 🧪 Test-Ready Architecture — Inject custom http.Client instances to easily mock and test geocoding in your apps.
  • 💯 100% Backward Compatible — Existing code using GeocoderPro.getDataFromCoordinates or GeocoderPro.getDataFromAddress continues to work seamlessly.

📊 Providers Overview

Feature OpenStreetMap (Nominatim) Google Maps API
API Key Required ❌ No (100% Free) ✅ Yes
Forward Geocoding ✅ Yes ✅ Yes
Reverse Geocoding ✅ Yes ✅ Yes
Multiple Results ✅ Yes ✅ Yes
Language Support ✅ Yes ✅ Yes
Component Filtering ✅ Country codes ✅ Countries, postal codes, admin areas
Bounding Box Bias ✅ Yes ✅ Viewport & Bounds

📦 Installation

Add geocoder_pro to your pubspec.yaml:

dependencies:
  geocoder_pro: ^1.1.0

Then import the library:

import 'package:geocoder_pro/geocoder_pro.dart';

🚀 Quick Start

1. Free OpenStreetMap Geocoding (No API Key Required)

// Forward Geocoding (Address -> Coordinates)
final geoData = await GeocoderPro.nominatim().getDataFromAddress('Eiffel Tower, Paris');

if (geoData != null) {
  print('Address: ${geoData.formattedAddress}');
  print('Latitude: ${geoData.latitude}, Longitude: ${geoData.longitude}');
  print('City: ${geoData.city}, Country: ${geoData.country}');
}

// Reverse Geocoding (Coordinates -> Address)
final reverseData = await GeocoderPro.nominatim().getDataFromCoordinates(
  latitude: 48.8584,
  longitude: 2.2945,
);

print('Resolved Address: ${reverseData?.formattedAddress}');

2. Google Maps Geocoding

// Initialize Google Geocoder
final googleGeocoder = GeocoderPro.google(apiKey: 'YOUR_GOOGLE_MAPS_API_KEY');

// Forward Geocoding
final data = await googleGeocoder.getDataFromAddress(
  '1600 Amphitheatre Pkwy, Mountain View, CA',
  language: 'en',
);

print('Coordinates: ${data?.latitude}, ${data?.longitude}');
print('State: ${data?.state}, Postal Code: ${data?.postalCode}');

// Reverse Geocoding
final loc = await googleGeocoder.getDataFromCoordinates(
  latitude: 37.4220,
  longitude: -122.0841,
);

print('Formatted Address: ${loc?.formattedAddress}');

3. Static Helper Methods (Backward Compatible)

Existing static methods remain fully supported:

// Google Maps Reverse Geocoding
GeoData? data = await GeocoderPro.getDataFromCoordinates(
  latitude: 40.714224,
  longitude: -73.961452,
  googleMapApiKey: 'YOUR_API_KEY',
  language: 'en',
);

// Google Maps Forward Geocoding
GeoData? place = await GeocoderPro.getDataFromAddress(
  address: '277 Bedford Ave, Brooklyn, NY 11211, USA',
  googleMapApiKey: 'YOUR_API_KEY',
);

You can also use the provider-agnostic fromAddress and fromCoordinates methods which automatically default to OpenStreetMap if no API key is specified:

// Automatically uses OpenStreetMap when apiKey is omitted
final data = await GeocoderPro.fromAddress('Colosseum, Rome');

4. Fetching Multiple Matching Locations

final List<GeoData> results = await GeocoderPro.nominatim()
    .getAddressesFromAddress('Springfield', limit: 5);

for (final item in results) {
  print('${item.formattedAddress} -> (${item.latitude}, ${item.longitude})');
}

📐 Spatial Utilities & Distance Calculations

GeocoderPro includes spatial tools powered by the Haversine formula:

const nyLat = 40.7128, nyLon = -74.0060;
const lonLat = 51.5074, lonLon = -0.1278;

// 1. Great-Circle Distance
final double distanceKm = GeoUtils.distanceBetweenKm(nyLat, nyLon, lonLat, lonLon);
final double distanceMiles = GeoUtils.distanceBetweenMiles(nyLat, nyLon, lonLat, lonLon);
print('Distance: $distanceKm km ($distanceMiles miles)'); // ~5570 km

// 2. Initial Compass Bearing
final double bearing = GeoUtils.bearingBetween(nyLat, nyLon, lonLat, lonLon);
print('Bearing: $bearing°'); // e.g. 51.2° (NE)

// 3. Geofencing Check
final bool isNearby = GeoUtils.isWithinRadius(
  centerLatitude: nyLat,
  centerLongitude: nyLon,
  targetLatitude: 40.7306,
  targetLongitude: -73.9352,
  radiusInMeters: 10000, // 10 km radius
);

// 4. Coordinates DMS Formatting
final String dms = GeoUtils.formatCoordinates(40.7128, -74.0060, dms: true);
print(dms); // 40° 42' 46.1" N, 74° 0' 21.6" W

// 5. Human-Readable Distance Formatter
print(GeoUtils.formatDistance(350));    // "350 m"
print(GeoUtils.formatDistance(2500));   // "2.5 km"
print(GeoUtils.formatDistance(5000, imperial: true)); // "3.11 mi"

🛡️ Robust Error Handling

geocoder_pro provides structured, typed exceptions so your app can handle API and network issues gracefully:

try {
  final result = await GeocoderPro.google(apiKey: 'INVALID_KEY')
      .getDataFromAddress('Paris, France');
} on ApiKeyException catch (e) {
  print('API Key Issue: ${e.message}');
} on QuotaExceededException catch (e) {
  print('Rate limit or billing quota exceeded: ${e.message}');
} on NetworkException catch (e) {
  print('Network/Connection error: ${e.message}');
} on GeocoderException catch (e) {
  print('General Geocoding error: ${e.message}');
}

🧪 Unit Testing with Custom HTTP Clients

All providers support injecting a custom http.Client:

import 'package:http/testing.dart';

final mockClient = MockClient((request) async {
  return http.Response(myMockJsonResponse, 200);
});

final geocoder = GeocoderPro.google(
  apiKey: 'TEST_KEY',
  client: mockClient,
);

final result = await geocoder.getDataFromAddress('Test Address');

📱 Interactive Example App

Check out the example/ folder for a complete Material 3 Flutter application featuring:

  • Live Forward Geocoding with quick presets
  • Live Reverse Geocoding with coordinate inputs
  • Distance, Bearing & Geofence Calculator
  • Interactive Provider Switch (Free OpenStreetMap & Google Maps)
  • Raw JSON Inspector modal

📝 License

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

🤝 Contributing

Contributions, issues, and feature requests are welcome! Feel free to check the issues page.

Libraries

geocoder_pro