bd_offline_geocoder

Offline Bangladesh reverse geocoder for Flutter.

GPS → Bangladesh address parts: house, road, area/village, union/ward, thana/upazila, district, division, postal code, city.

No API key. No network. Same data as Python and npm.

Keywords: Bangladesh geocoder, Flutter offline location, GPS to upazila, ward, thana, Dhaka street.

final geocoder = await BdOfflineGeocoder.fromBundledAssets();
final result = geocoder.reverse(latitude: 23.74015, longitude: 90.38286);
print(result.formatted);
// House 3, Road 3, Dhanmondi, Ward No-49, Dhanmondi Thana, Dhaka 1209, Bangladesh
print(result.toJson());

Features

Offline after install — no Maps SDK
Bundled ADM1–ADM4 GeoJSON
Dhaka named roads + house-number points (OSM)
Polygon / MultiPolygon with holes
Bounding-box filter, then ray-casting
fromBundledAssets() loads layers in parallel
Web-safe: fromFile is stubbed; use assets or fromString

Install

dependencies:
  bd_offline_geocoder: ^0.1.1

flutter pub add bd_offline_geocoder

Dart 3.4+ · Flutter 3.16+. Archive is large because the full boundary set is included.

Load the geocoder once (initState, Riverpod, GetIt) and reuse it.

Usage

import 'package:bd_offline_geocoder/bd_offline_geocoder.dart';

final geocoder = await BdOfflineGeocoder.fromBundledAssets();
final result = geocoder.reverse(latitude: 23.74015, longitude: 90.38286);

result.houseNumber;   // 3
result.roadNumber;    // 3
result.roadName;
result.areaVillage;   // Dhanmondi
result.unionWard;     // Ward No-49
result.thanaUpazila;  // Dhanmondi Thana
result.district;      // Dhaka
result.division;      // Dhaka
result.postalCode;    // 1209
result.city;          // Dhaka
result.toJson();

Outside Bangladesh: found == false and
This geocoder only supports locations inside Bangladesh.

Dart CLI / files

final divisions = await GeoJsonBoundarySource.fromFile(
  'assets/boundaries/bgd_admin1.geojson',
  id: 'divisions',
  type: GeocoderLayerType.division,
  namePropertyCandidates: ['adm1_name'],
);
final geocoder = BdOfflineGeocoder(layers: [divisions]);

On web, fromFile throws. Use fromBundledAssets() or fromString.

Example app

https://github.com/TasfiqulGhani/bd-offline-geocoder/tree/main/examples/flutter_app

cd examples/flutter_app && flutter pub get && flutter run

Limits

Nationwide: administrative polygons (ADM4 simplified).
Road / house: central Dhaka OSM only; house numbers are sparse.

Links


Source	https://github.com/TasfiqulGhani/bd-offline-geocoder
Architecture	https://github.com/TasfiqulGhani/bd-offline-geocoder/blob/main/docs/ARCHITECTURE.md
Python	https://pypi.org/project/bd-offline-geocoder/
npm	https://www.npmjs.com/package/bd-offline-geocoder

Author: Tasfiqul Ghani. MIT code; see notices.