JP Data (Japanese Public Business Data)

jp-data-mcp — Japanese Public Business Data for AI Agents

A free, open-source MCP server that gives AI agents the Japanese business-data primitives they most often need:

• Corporate numbers (法人番号) — offline check-digit validation and, with a (free) NTA application ID, live registry enrichment from the National Tax Agency 法人番号 Web-API: registered name, address, entity kind, dates.
• Zengin bank / branch codes (統一金融機関コード・支店コード) — the codes that describe a Japanese domestic bank transfer, with kana / hiragana / romaji.
• Japanese national holidays — official Cabinet Office holiday data, bundled.

It runs entirely on your machine. No account, no API key of ours, no payments, no telemetry — usage is not logged or reported anywhere.

Tools

Important: the SYNTHETIC_SAMPLE fallback

Live corporate-registry data requires a free NTA Web-API application ID (register at the 国税庁 法人番号システム Web-API site), supplied via the NTA_APP_ID environment variable.

Without `NTA_APP_ID`, lookup_corporate_number and search_corporations_by_name fall back to a tiny bundled synthetic sample set. These records are fabricated for testing, do not correspond to real companies, and every one of them is tagged "source": "SYNTHETIC_SAMPLE" plus an explanatory note in the response — they can never be mistaken for real registry data. Check-digit validation and the bank/holiday tools do not need any key and always use real data.

Known limitation: the NTA v4 CSV column mapping is written from the published spec but has not yet been verified against a live API response. If you find a misaligned field, please open an issue.

Install & run

Requires Python 3.11+.

git clone https://github.com/kimotostudio/jp-data-mcp.git

cd jp-data-mcp pip install fastmcp httpx # or: uv sync python src/server.py # stdio MCP server

Or with uv, no explicit install step:

uv run --directory /path/to/jp-data-mcp src/server.py

Claude Desktop / MCP client config (stdio)

{

"mcpServers": { "jp-data": { "command": "uv", "args": ["run", "--directory", "/path/to/jp-data-mcp", "src/server.py"], "env": { "NTA_APP_ID": "your-nta-app-id (optional)" } } } }

An .mcpb bundle (usable with MCPB-aware clients) is attached to each GitHub release.

Local HTTP mode (optional)

python src/server.py --http   # streamable-http on 127.0.0.1:8765 (localhost only)

Test

python test_client.py

Data sources & licenses

Disclaimer

This project is not affiliated with or endorsed by the National Tax Agency, the Japanese Bankers Association, the zengin-code project, or the Cabinet Office. Data is provided as-is with no warranty of accuracy or completeness — verify against official sources before relying on it for legal, tax, accounting, or payment decisions. Bundled datasets are snapshots and may lag the official sources.

License

MIT

Local review

See the local tool walkthrough for a synthetic example and test scope.