OTP Generator Pro

#otp-generator-pro

A secure, easy-to-use, and highly configurable OTP (One-Time Password) generator for Node.js applications with extensive customization options.

Installation

npm install @yashdatoniya/otp-generator-pro

Quick Start

const {generateOTP} = require('@yashdatoniya/otp-generator-pro');

// Generate a simple 6-digit OTP

const otp = generateOTP();
console.log(otp);

// Generate a custom length & character types
const customOTP = generateOTP({
length: 8,
digits: true,
lowerCase: true,
upperCase: true,
specialChars: true
});
console.log(customOTP);

// Generate OTP with expiration time

const otpWithExpiration = generateOTP({expiresIn: "5m"});
console.log(otpWithExpiration);

/*
{
otp: "789843",
expiresAt: 2025-06-25T10:35:00.000Z,
createdAt: 2025-06-25T10:30:00.000Z,
expiresIn: 300
}
*/

API Reference

1. generateOTP(options)

Generates an OTP with custom configuration options.

Parameters

options (Object): Configuration object

• length (number): Length of the OTP (default: 6, min: 1, max: 32)
• digits (boolean): Include digits 0-9 (default:true)
• lowerCase (boolean): Include lowercase letters a-z (default: false);
• upperCase (boolean): Include uppercase letters A-Z (default: false)
• specialChars (boolean): Include special characters (default: false);
• customChars (string): Custom character set to use;
• expireIn (number|string): seconds or string '5m', '1h', etc;

Returns

• Without expiration: string: Generated OTP
• With expiration: object: Object containing OTP and expiration details

// Default 6-digit numeric OTP
const otp = generateOTP(); // "123456"

// Custom length
const longOtp = generateOTP({ length: 8 });
// "12345678"

// 8-character alphanumeric OTP

const alphaOtp = generateOTP({
  length: 8,
  digits: true,
  lowerCase: true,
  upperCase: true,
});
// "A7b2X9k1"

// Custom character set
const customOtp = generateOTP({
  length: 6,
  customChars: "ABCDEF123456",
});
// "AB3C5F"

//With expiration
generateOTP({
  length: 6,
  digits: true,
  expiresIn: "5m",
});
// "234567"

// With expiration (number in seconds)
const otpWithExpiry = generateOTP({ expiresIn: 300 });

// With expiration (string format)
const otpWithStringExpiry = generateOTP({ expiresIn: "5m" });

3. generateNumericOTP(length, expiresIn)

Generate numeric-only OTP (digits 0-9).

const numericOtp = generateNumericOTP(6);
// "123456"

const numericWithExpiry = generateNumericOTP(8, "10m");
// Returns object with 8-digit numeric OTP and 10-minute expiration

4. generateAlphaNumericOTP(length, expiresIn)

Generate alpha-numeric OTP (digits + letters).

const alphaNumOtp = generateAlphaNumericOTP(8);
// "A3b7K9m2"

const alphaNumWithExpiry = generateAlphaNumericOTP(12, "1h");
// Returns object with 12-character alphanumeric OTP and 1-hour expiration

5.generateComplexOTP(length, expiresIn)

Generate complex OTP with all character types.

const complexOtp = generateComplexOTP(12);
// "A3b7K9m2!@#"

const complexWithExpiry = generateComplexOTP(16, "30m");
// Returns object with 16-character complex OTP and 30-minute expiration

Expiration Time Formats

The expiresIn parameter accepts:

• Number: Time in seconds
• String: Time with unit suffix

| Format | Description | Examples | | :----- | :---------- | :------- | | 30 | 30 seconds | 30 | | 30s | 30 seconds | 30s | | 5m | 5 minutes | 5m | | 1h | 1 hours | 1h | | 1d | 1 day | 1d |

Expiration Response Object

When expiresIn is provided, the function return an object:

{
  otp: "123456",              // The generated OTP
  expiresAt: Date,            // Expiration timestamp
  createdAt: Date,            // Creation timestamp
  expiresIn: 300              // Expiration time in seconds
}

Character Sets

Default Character Sets

• Digits: 0123456789
• Lowercase: abcdefghijklmnopqrstuvwxyz
• Uppercase: ABCDEFGHIJKLMNOPQRSTUVWXYZ
• Special Characters: !@#$%^&*()_-+=[]{}|:;,.<>?

Custom Character Sets

You can provide your own character set using the customChars option:

const otp = generateOTP({
  length: 8,
  customChars: "0123456789ABCDEF", // Hexadecimal characters only
});

Error Handling

The library provides clear error message for invalid inputs

// Invalid length
generateOTP({ length: 0 });
// Error: OTP length must be between 1 to 32 characters

// Invalid expiration format
generateOTP({ expiresIn: "invalid" });
// Error: Invalid expiration format. Use number (second) or string like "5m", "1h", "30s"

// Invalid time unit
generateOTP({ expiresIn: "5x" });
// Error: Invalid expiration format. Use number (second) or string like "5m", "1h", "30s"

Usage Examples

Email Verification

const { generateNumericOTP } = require("@yashdatoniya/otp-generator-pro");

// Generate 6-digit OTP valid for 10 minutes
const emailOtp = generateNumericOTP(6, "10m");

console.log(`Your verification code: ${emailOtp.otp}`);
console.log(`Expires at: ${emailOtp.expiresAt.toLocaleString()}`);

SMS Authentication

const { generateOTP } = require("@yashdatoniya/otp-generator-pro");

// Generate 4-digit OTP for SMS (shorter for mobile)
const smsOtp = generateOTP({
  length: 4,
  digits: true,
  expiresIn: "5m",
});

console.log(`SMS Code: ${smsOtp.otp}`);

Two-Factor Authentication

const { generateAlphaNumericOTP } = require("@yashdatoniya/otp-generator-pro");

// Generate 8-character alphanumeric code for 2FA
const twoFactorCode = generateAlphaNumericOTP(8, "15m");

console.log(`2FA Code: ${twoFactorCode.otp}`);

Secure Token Generation

const { generateComplexOTP } = require("@yashdatoniya/otp-generator-pro");

// Generate complex token for secure operations
const secureToken = generateComplexOTP(32, "1h");

console.log(`Secure Token: ${secureToken.otp}`);

Features

Cryptographically Secure: Uses Node.js crypto module for secure random generation.

Highly Customizable: Configure length, character sets, exclusions, and more.

Multiple Presets: Numeric, alphanumeric, and complex OTP generators.

Validation: Built-in OTP validation functionality.

Zero Dependencies: Lightweight with no external dependencies

TypeScript Support: Full TypeScript declarations included

Testing

Run the comprehensive test suite:

npm test

Keywords

otp generator one-time-password security