Chilean RUT Formatter

High-performance TypeScript library for formatting and validating Chilean RUTs (Rol Único Tributario).

Features

• ✅ Validate RUTs using the official Module 11 algorithm
• ✅ Format with customizable options (dots, dashes, case)
• ✅ Clean and sanitize user input
• ✅ TypeScript - Full type definitions included
• ✅ Zero dependencies - Lightweight and fast
• ✅ Secure - Input sanitization and DoS protection
• ✅ Tree-shakeable - ESM and CJS support

Installation

npm install chilean-rut-formatter

Usage

Validate a RUT

import { validateRut, isValidRut } from 'chilean-rut-formatter';

// Full validation with details
const result = validateRut('12.345.678-5');
// { isValid: true, rut: '123456785' }

const invalid = validateRut('12345678-0');
// { isValid: false, error: 'Invalid verification digit' }

// Simple boolean check
isValidRut('12.345.678-5'); // true
isValidRut('12345678-0');   // false

Format a RUT

import { formatRut } from 'chilean-rut-formatter';

// Default: with dots and dash
formatRut('123456785');         // '12.345.678-5'
formatRut('12345678K');         // '12.345.678-K'

// Custom options
formatRut('123456785', { dots: false });       // '12345678-5'
formatRut('123456785', { dash: false });       // '12.345.6785'
formatRut('12345678K', { uppercase: false });  // '12.345.678-k'

// Returns empty string if RUT is invalid
formatRut('12345678-0');  // ''

Format Partial Input (Real-time)

import { formatRutPartial } from 'chilean-rut-formatter';

// Great for live formatting as user types
formatRutPartial('1');         // '1'
formatRutPartial('12');        // '1-2'
formatRutPartial('12345');     // '1.234-5'
formatRutPartial('123456789'); // '12.345.678-9'

Clean a RUT

import { cleanRut } from 'chilean-rut-formatter';

cleanRut('12.345.678-9');    // '123456789'
cleanRut('12 345 678-k');    // '12345678K'
cleanRut('  12#345$678%9 '); // '123456789'

Calculate Verification Digit

import { calculateVerificationDigit } from 'chilean-rut-formatter';

calculateVerificationDigit('12345678');  // '5'
calculateVerificationDigit('16612277');  // 'K'

API Reference

validateRut(rut: string): ValidationResult

Validates a Chilean RUT and returns detailed result.

interface ValidationResult {
  isValid: boolean;
  rut?: string;    // Cleaned RUT if valid
  error?: string;  // Error message if invalid
}

isValidRut(rut: string): boolean

Simple boolean validation check.

formatRut(rut: string, options?: FormatOptions): string

Formats a valid RUT. Returns empty string if RUT is invalid.

interface FormatOptions {
  dots?: boolean;      // Include dots (default: true)
  dash?: boolean;      // Include dash (default: true)
  uppercase?: boolean; // Uppercase K (default: true)
}

formatRutPartial(rut: string, options?: FormatOptions): string

Formats partial RUT input (useful for real-time formatting).

cleanRut(input: string): string

Removes all non-valid characters from input.

calculateVerificationDigit(rutBody: string): string

Calculates the verification digit for a RUT body.

Security

• Input Sanitization: All inputs are cleaned before processing
• DoS Protection: Maximum input length enforced (50 chars)
• No eval/Function: No dynamic code execution
• TypeScript Strict Mode: Full type safety

Performance

• Zero dependencies: No external library overhead
• Pre-compiled regex: Patterns compiled once at module load
• Early returns: Fast failure for invalid inputs
• Minimal allocations: Optimized for performance

License

MIT