skanfirmy.pl — MCP server

A free, stateless MCP (Model Context Protocol) server that lets AI agents verify Polish companies and validate EU VAT numbers directly from official government registers — no key, no registration, no limits beyond the source registries' own.

• Endpoint: https://skanfirmy.pl/mcp (JSON-RPC 2.0 over Streamable HTTP)
• 9 tools combining the VAT Register (Ministry of Finance), KRS (Ministry of Justice), REGON (Statistics Poland / GUS) and VIES (European Commission).
• Also usable as plain REST for crawlers/agents that can't speak MCP.

Made by Bartosz Kuć — the same person behind skanfirmy.pl and the otwarteAPI.pl catalog of Polish & EU public APIs.

Tools

Tool	What it does
sprawdz_nip	VAT status (Biała Lista) + KRS data for a company by NIP
sprawdz_lista_nip	Bulk lookup of up to 30 NIPs in one call (MF VAT Register)
sprawdz_regon	REGON registry data (GUS) by NIP — incl. sole traders not in KRS
sprawdz_vies	Validate an EU VAT number via VIES (European Commission)
sprawdz_rachunek	Is a bank account on the VAT White List for a given NIP
generuj_mikrorachunek	Individual tax micro-account (PIT/CIT/VAT) from NIP/PESEL
szukaj_pkd	Search the PKD 2025 business-activity classification
oblicz_odsetki	Statutory / commercial (B2B) late-payment interest calculator
szukaj_katalog_api	Search otwarteAPI.pl — a catalog of other public PL/EU APIs

Connect

Any MCP client that supports remote (Streamable HTTP) servers — point it at:

https://skanfirmy.pl/mcp

Claude Desktop / stdio-only clients — bridge with mcp-remote:

{
  "mcpServers": {
    "skanfirmy": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://skanfirmy.pl/mcp"]
    }
  }
}

Raw JSON-RPC (no MCP client needed):

# list tools
curl -s https://skanfirmy.pl/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

# check a company by NIP
curl -s https://skanfirmy.pl/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"sprawdz_nip","arguments":{"nip":"5261040828"}}}'

Plain REST (no MCP)

For agents/crawlers that just want a URL:

• GET https://skanfirmy.pl/nip/{nip} — VAT + KRS
• GET https://skanfirmy.pl/nips/{comma,separated,nips} — bulk (≤30)
• GET https://skanfirmy.pl/regon/{nip} — REGON registry data
• GET https://skanfirmy.pl/vies/{country}/{number} — EU VAT (VIES)

Add ?format=json for JSON. Full docs: skanfirmy.pl/llms.txt.

Claude Agent Skill

Prefer a drop-in Agent Skill? skill/ holds verify-polish-company — a single SKILL.md that teaches Claude Code, the Claude apps or the Agent SDK when and how to call the endpoints above (no key, nothing to run beyond ordinary HTTP):

cp -R skill ~/.claude/skills/verify-polish-company

See skill/README.md for details.

Data sources

VAT Register / Biała Lista (Ministry of Finance), KRS (Ministry of Justice), REGON / BIR (Statistics Poland — GUS), VIES (European Commission). Independent project — not affiliated with any of them. Nothing is persisted; responses are transiently CDN-cached (max 24h), POST /mcp isn't cached at all.

Author

Bartosz Kuć · skanfirmy.pl · github.com/bartosz-kuc · linkedin.com/in/bartosz-kuc · cal.com/bartosz-kuc

License

MIT © Bartosz Kuć. This repository documents the hosted server and holds its MCP registry manifest; the server itself runs at https://skanfirmy.pl/mcp.