Polish Open Data (unofficial) MCP server

PolishOpenData

.NET libraries and an MCP server for Polish public registers — company lookup in KRS, the VAT whitelist (Biała Lista) with bank-account checks, and offline validation of NIP, REGON, KRS, NRB and land-registry (KW) numbers.

🇵🇱 Polska wersja

Unofficial project. Not affiliated with the Ministry of Justice, the Ministry of Finance or any other public body. Results are informational, not legal or tax advice; the registers are the authoritative source.

Packages

Offline validation

No network, no DI:

dotnet add package PolishOpenData.Core

using PolishOpenData;

Console.WriteLine(Nip.TryParse("774-000-14-54", out var nip) ? $"Valid NIP {nip}" : "Invalid NIP"); // Valid NIP 7740001454
Console.WriteLine(KwNumber.TryParse("WA1M/00012345/1", out var kw) ? kw.Court?.Name : "Invalid KW number"); // Sąd Rejonowy dla Warszawy-Mokotowa …
Console.WriteLine(string.Join(", ", KwNumber.SuggestCorrections("WAIM/00012345/1"))); // WA1M/00012345/1

Quick start: check a counterparty

dotnet add package PolishOpenData.BialaLista
dotnet add package PolishOpenData.Krs
dotnet add package Microsoft.Extensions.Http.Resilience

using Microsoft.Extensions.DependencyInjection;
using PolishOpenData;
using PolishOpenData.BialaLista;
using PolishOpenData.Krs;
using System.Threading.Tasks;

var services = new ServiceCollection();
services.AddBialaListaClient(o => o.TrackQuota = true)
    .AddStandardResilienceHandler(o => o.Retry.ShouldHandle = _ => new ValueTask<bool>(false));
services.AddKrsClient().AddStandardResilienceHandler();
using var provider = services.BuildServiceProvider();

var vat = provider.GetRequiredService<IBialaListaClient>();
var nip = Nip.Parse("774-000-14-54");

var result = await vat.FindByNipAsync(nip);
Console.WriteLine($"{result.Value?.Name}: {result.Value?.VatStatus} (request {result.RequestId})");

var check = await vat.CheckBankAccountAsync(nip, Nrb.Parse("06 1600 1127 1843 9838 2000 0034"));
Console.WriteLine(check.Value ? "Account is on the whitelist" : "Account is NOT on the whitelist");

var krs = provider.GetRequiredService<IKrsClient>();
var extract = await krs.GetCurrentExtractAsync(result.Value!.Krs!.Value);
Console.WriteLine(extract.Extract?.ToSummary().ShareCapital);

Shortened. The full README is on GitHub.