Package Exports

kvnr-utils
kvnr-utils/dist/index.js

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Readme

KVNR Utils

A lightweight TypeScript library for validating and formatting German Health Insurance Numbers (Krankenversichertennummer - KVNR).

Purpose

This library provides validation-only functionality for German Health Insurance Numbers:

Format validation: Checks syntax and structure
Check digit validation: Verifies mathematical correctness using official Luhn algorithm
Input normalization: Handles whitespace and case variations

Features

Validates format and check digit using the official modified Luhn algorithm
Handles user input with whitespace and case variations
Full type definitions included
Lightweight with no external dependencies
Well-tested with Jest
Framework-agnostic (works everywhere JavaScript runs)

Installation

npm install kvnr-utils

Compatibility

This library is framework-agnostic and works with:

Vanilla JavaScript/TypeScript (ES2020+)
React (any version)
Angular (any version)
Vue.js (any version)
Node.js (v14+)
Next.js, Nuxt.js, SvelteKit etc.
Webpack, Vite, Rollup - all bundlers
Browser & Server-Side environments

No dependencies - works everywhere JavaScript runs!

Usage

import { isValidKVNR, normalizeKVNR } from 'kvnr-utils';

// Validate a KVNR
const isValid = isValidKVNR('A123456780'); // true (if check digit is correct)

// Normalize user input
const normalized = normalizeKVNR(' a123456780 '); // 'A123456780'

Framework Examples

React:

import { isValidKVNR } from 'kvnr-utils';

function KVNRInput() {
  const [kvnr, setKvnr] = useState('');
  const isValid = isValidKVNR(kvnr);
  
  return (
    <input 
      value={kvnr} 
      onChange={(e) => setKvnr(e.target.value)}
      className={isValid ? 'valid' : 'invalid'}
    />
  );
}

Angular:

import { isValidKVNR } from 'kvnr-utils';

@Component({...})
export class KVNRComponent {
  kvnr = '';
  
  get isValid() {
    return isValidKVNR(this.kvnr);
  }
}

KVNR Format

A German Health Insurance Number (KVNR) consists of:

Position 1: Random uppercase letter (A-Z, no umlauts)
Positions 2-9: Eight random digits
Position 10: Check digit calculated using modified Luhn algorithm

Validation Algorithm

This library implements the official German specification for KVNR validation:

Format check: Validates the pattern ^[A-Z][0-9]{9}$
Letter conversion: Converts A-Z to 01-26
Modified Luhn algorithm:
- Multiply digits alternately with weights 1-2-1-2-1-2-1-2-1-2
- Calculate cross sum of each product
- Sum all cross sums
- Check digit = sum modulo 10

Source: Wikipedia - Krankenversichertennummer

API Reference

`isValidKVNR(kvnr: string): boolean`

Validates a KVNR string.

Parameters: kvnr - The KVNR string to validate
Returns: true if valid, false otherwise

`normalizeKVNR(kvnr: string): string`

Normalizes a KVNR string by trimming whitespace and converting to uppercase.

Parameters: kvnr - The raw KVNR string
Returns: Normalized KVNR string

Development

# Install dependencies
npm install

# Run tests
npm test

# Build
npm run build

kvnr-utils