SayWhere

Geocoding with Words - Convert coordinates to memorable phrases

Encode Coordinates

Add altitude (optional)

Decode Phrase

Results

Help & Information

About SayWhere

SayWhere is an open-source, deterministic algorithm that converts geographic coordinates to memorable word phrases and back. It provides a human-friendly way to share precise locations using memorable words instead of complex coordinates.

Key Features:

  • Deterministic: Same coordinates always produce same words
  • Reversible: Perfect roundtrip accuracy (within grid precision)
  • Error Detection: Checksum word validates typos and wordlist version
  • 3D Positioning: Optional altitude for multi-level structures (e.g., building floors)
  • Open Source: Fully transparent algorithm under GPL-3.0 license
  • Self-Contained: No external API dependencies
  • Fast: Sub-50ms encoding/decoding

How it works

SayWhere converts geographic coordinates into memorable word phrases using the BIP-39 wordlist. Each phrase represents a location with varying precision:

  • 1 word: Regional (~900km) - countries/regions
  • 2 words: Metro (~27km) - metro areas
  • 3 words: Neighborhood (~900m) - neighborhoods
  • 4 words: Street (~27m) - buildings
  • 5 words: Door (~90cm) - entrances (recommended)
  • 6 words: Precise (~2.7cm) - exact positions

Features:

  • Hierarchical phrases with true prefix relationships
  • Two-layer error detection: per-word parity + optional CRC-8 terminal checksum
  • Privacy-preserving (all processing is client-side)
  • Shareable URLs for easy location sharing

View on Codeberg

© 2025 SayWhere Contributors. Open source under GPL-3.0 license.

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