Show HN: Offline map of Budapest listing embassies (150 megabyte download)

Map Data & Imagery

OpenStreetMap Contributors © OpenStreetMap contributors

The base map tiles are provided by OpenStreetMap, a collaborative project to create a free editable map of the world. Map data is available under the Open Database License (ODbL).

https://www.openstreetmap.org/copyright

Core Technologies

Python PIL/Pillow - Image processing and tile generation

• Fredrik Lundh and Contributors (Python Imaging Library)
• Alex Clark and Contributors (Pillow fork)

IndexedDB API - Browser-based storage for offline functionality

• W3C Web Applications Working Group specification

Development Tools & Libraries

• HTML5 Canvas API - Minimap visualization
• Web Workers API - Background processing capabilities
• FileReader API - Local file handling
• Geolocation API - User location services

Data Processing

CSV data format and embassy/consulate location data - Provided by project owner

Coordinate transformation algorithms - Based on Web Mercator projection (EPSG:3857) and standard tile mapping mathematics

Technical References

Slippy map tilenames - OpenStreetMap Wiki contributors

Tile coordinate and zoom level calculations based on OSM tile naming conventions

Web Mercator Projection - Mathematical formulas for lat/lon to pixel conversions

Development Assistance

Claude (Anthropic) - AI assistance with code generation, debugging, and system architecture

Special Thanks

• The OpenStreetMap volunteer mapping community for maintaining free and open map data
• The open source community for the tools and libraries that made this project possible
• Budapest's municipal government for maintaining open geographic data
• Contributors to the Web standards that enable offline-first progressive web applications

License Note

This application generates derivative works from OpenStreetMap data. Any redistribution must maintain appropriate attribution and comply with the ODbL license terms.