Klarfakt 1.0.0-preview.2

Klarfakt

Read and validate EN 16931 electronic invoices in .NET — no Java, no Node.js, no native dependencies, and nothing leaves your server.

Klarfakt runs the publishers' own compiled Schematron in-process: the same artefacts the German reference validator executes, fetched from their pinned upstream releases and checked against a recorded SHA-256. 97 of 97 comparable files agree rule for rule with KoSIT's validationtool on every CI run.

using Klarfakt;
using Klarfakt.Validation;

var catalog = RulePackCatalog.Load();
if (!catalog.IsRestored) await catalog.RestoreAsync();   // once, at deployment or build

// Compiling takes seconds, validating takes milliseconds. Keep one; it is thread-safe.
var validator = new InvoiceValidator(catalog);

var document = InvoiceDocument.Load("invoice.xml");      // or a Factur-X / ZUGFeRD PDF
var result = validator.Validate(document);               // rule set chosen from the invoice itself

foreach (var error in result.Errors)
{
    Console.WriteLine($"{error.RuleId} at {error.Location}: {error.Message}");
}

BR-CL-04 at /ubl-invoice:Invoice/cbc:DocumentCurrencyCode: Invoice currency code
MUST be coded using ISO code list 4217 alpha-3

What it covers

Findings carry the rule id, severity, location, the failing XPath test, the BT/BG business terms, the offending value where the rule pointed at one, and which artefact produced them — so a CEN core rule is distinguishable from a German CIUS rule.

Rule artefacts

They are not in this package. The CEN rules are EUPL-1.2 and the KoSIT configurations are Apache-2.0, so they stay with their publishers and are downloaded on request:

klarfakt rules restore

Plain HTTPS from the pinned upstream release, every file checked against the SHA-256 in the embedded manifest before it is written, and again before first use. Nothing else in Klarfakt touches the network. Set KLARFAKT_RULES to point at a directory you manage yourself for air-gapped deployments.

Licence

Free unless your organisation turns over more than €1,000,000 a year. Free at any size inside OSI-licensed open source. Free always for evaluation, development, CI and internal testing.

Above that threshold and in production, a commercial licence is €690 a year for unlimited developers, deployments and validations, covering every version released during the term permanently. Every version becomes Apache 2.0 four years after it ships — 1.x on 2030-09-04. Terms are Business Source License 1.1, which is not an OSI-approved licence.

Documentation, samples and source · licensing@klarfakt.dev