jp-address-romaji-data

The offline Japanese address dataset used by jp-address-romaji.

npm install jp-address-romaji jp-address-romaji-data

Installing it is all you need to do — jp-address-romaji finds it automatically, and every conversion then runs locally with no network access.

ESM only, Node.js 18+. This package exists to be installed alongside the library, not used on its own; see the library's requirements.

What's in it

638,567 town (machi-aza) entries across 1,898 municipalities, in the same layout the upstream Geolonia v2 API serves:

data/ja.json                  prefectures + municipalities
data/ja/<pref>/<city>.json    towns of one municipality

Two things are deliberately excluded:

• Coordinates on town records. This library makes no geocoding accuracy claim, so representative points would add tens of megabytes of data it never reads. They are kept on prefecture and city records, which upstream requires.
• Street-level data (residential display and parcel numbers). Block numbers are digits and need no lookup; only town-level names carry readings that cannot be derived.

Building the dataset yourself

npx jp-address-romaji-data build --out ./address-data

That contacts Geolonia once. Converting addresses never does.

import { configureDataSource } from 'jp-address-romaji';
configureDataSource({ dataDir: './address-data' });

Other commands: where prints the bundled dataset directory, status reports whether it has been generated.

Data source and licensing

The data originates from the Japanese Digital Agency's Address Base Registry (アドレス・ベース・レジストリ), processed and published by Geolonia. See ATTRIBUTION.md for the full statement and links.

The build tooling in this package is MIT licensed.