What3Words

Overview

what3words divides the world into 3m×3m squares, each with a unique three-word address (e.g. ///filled.count.soap). Their API converts coordinates ↔ 3-word addresses, autocompletes partial words, and handles voice input — a distinctive option for delivery, emergency, and location-sharing apps.

Note: the API requires a free API key (verified: invalid keys return 401). Registration is at what3words.com/select-plan (free tier available).

Quick Start

Coordinates → 3-word address (replace YOUR_KEY):

curl "https://api.what3words.com/v3/convert-to-3wa?coordinates=51.5074%2C0.1278&key=YOUR_KEY&language=en"

{
  "words": "filled.count.soap",
  "coordinates": { "lng": 0.1278, "lat": 51.5074 },
  "language": "en",
  "map": "https://w3w.co/filled.count.soap"
}

3-word address → coordinates:

curl "https://api.what3words.com/v3/convert-to-coordinates?words=filled.count.soap&key=YOUR_KEY"

Autosuggest (partial words):

curl "https://api.what3words.com/v3/autosuggest?input=filled.count.s&key=YOUR_KEY"

Authentication

• Register at what3words.com and generate an API key (free tier available).
• Send it as the key query parameter (an invalid key returns 401 — verified).

Rate Limits & Notes

• Free tier has request limits (check the pricing page — modest for evaluation); paid plans scale.
• 3-word addresses are language-localized (50+ languages) — pass language=en etc.
• autosuggest supports partial input with clip-to-country and n-results options.
• The map field links to the w3w.co viewer — handy for UI.

FAQ

Is what3words free? There’s a free tier (request-limited); paid plans for production scale.

How do I get a key? Register at what3words.com → select a plan → generate an API key.

What are 3-word addresses? Each 3m×3m square on Earth has a unique three-word identifier, e.g. ///filled.count.soap.