nip-krs-mcp

MCP server for Polish company registries. Look up any Polish company by NIP (tax id) or KRS (court registry number) from Claude Code, Claude Desktop, or any MCP-compatible AI client.

Uses two public government APIs — no authentication required. Data flows only between your machine and the official Polish government endpoints (Ministry of Finance + Ministry of Justice).

Why this exists

Every Polish business, accountant, or developer working with Polish data eventually needs to:

• Verify if a client's NIP is a real, active VAT payer
• Check if a vendor's invoice can be tax-deducted (VAT status on the invoice date)
• Look up a company's full legal registry entry — board members, capital, address history
• Confirm a bank account belongs to a whitelisted vendor (to avoid split-payment penalties)

Doing this manually via web forms is tedious. This MCP lets an AI do it in one shot.

Features (v0.1)

Two tools:

• lookup_by_nip — official Biała Lista MF entry. Returns: legal name, address, VAT status (Czynny / Zwolniony / Wykreślony), REGON, KRS, list of whitelisted bank accounts. Supports historical dates (up to 5 years back) — critical for tax-deductibility of past invoices.
• lookup_by_krs — full KRS registry entry. Returns: name, legal form, address, share capital, board members, PKD codes, shareholders. Supports both registers: P (Przedsiębiorcy — companies) and S (Stowarzyszenia — associations, foundations, NGOs).

Planned for v0.2:

• lookup_by_regon — GUS BIR API (requires free API key)
• search_by_name — fuzzy search across biała lista and KRS
• bulk_check_accounts — verify many bank accounts against biała lista in one call

Requirements

• Python 3.10+
• No API keys. No accounts. No signup. Both APIs are fully public.

Setup

git clone https://github.com/bartosz-kuc/nip-krs-mcp.git
cd nip-krs-mcp
python3 -m venv venv
./venv/bin/pip install -r requirements.txt

Register with Claude Code:

claude mcp add pl-registries /absolute/path/to/venv/bin/python /absolute/path/to/server.py

Or with Claude Desktop — edit claude_desktop_config.json:

{
  "mcpServers": {
    "pl-registries": {
      "command": "/absolute/path/to/venv/bin/python",
      "args": ["/absolute/path/to/server.py"]
    }
  }
}

Tools appear as mcp__pl-registries__lookup_by_nip etc.

Example usage

"Check if Google Poland is an active VAT payer."

AI calls lookup_by_nip("5252344078") → returns full biała lista entry with VAT status.

"What was Orange Polska's VAT status on 2025-11-15?"

AI calls lookup_by_nip("5260250995", date="2025-11-15") — status as of that date, important for confirming tax deductibility of an invoice you're posting late.

"Who's on the board of KRS 0000006042?"

AI calls lookup_by_krs("0000006042", register="P") → returns full registry entry with board composition.

Data flow

Your AI client
     ↕  MCP stdio
This server (Python, on your machine)
     ↕  HTTPS
Public Polish gov APIs (wl-api.mf.gov.pl, api-krs.ms.gov.pl)

No third party in the middle. No accounts. Nothing to breach.

Security notes

• Nothing to leak. No credentials, no tokens, no OAuth — this MCP has no secrets at all.
• Rate limits. Both APIs enforce rate limits (biała lista: 10 req/sec, KRS: similar). This client does not currently implement retry/backoff; a burst may return HTTP 429.
• Data is public. Anything this MCP returns is already public information you could pull manually from https://www.podatki.gov.pl/wykaz-podatnikow-vat/ or https://ekrs.ms.gov.pl/.

Author

Bartosz Kuć — Warsaw-based developer, JDG owner running skanfirmy.pl (Polish company verification tools).

• Site: https://skanfirmy.pl

• GitHub: https://github.com/bartosz-kuc

• Email: firma@bartosza.pl

Consulting

Available for consulting on Polish tax and business integrations (KSeF, GUS/NFZ/GIOŚ APIs, mBank data), MCP server design, and AI-assisted tooling for JDGs and small teams. See skanfirmy.pl/uslugi for productized packages (audit 3k PLN, setup 8-15k PLN, retainer 2-4k PLN/mo), or reach out via email.

License

MIT — see LICENSE.

Related

• honest-gmail-mcp — local Gmail MCP
• honest-calendar-mcp — local Google Calendar MCP
• ksef-mcp — Polish KSeF (e-invoicing) MCP