OTP Kit

A lightweight and extensible library for generating and verifying One-Time Passwords (OTPs).
Supports random OTPs (numeric, alphanumeric, custom charset), with planned support for TOTP and HOTP.

✨ Features

• Generate OTPs with numeric, alphabetic, alphanumeric, or custom charsets
• Configurable OTP length (default: 6)
• Secure verification using crypto.timingSafeEqual
• Optional expiry validation

📦 Installation

npm install otp-kit
# or
yarn add otp-kit

🚀 Usage

import { OtpKit } from "otp-kit";

# Create a random numeric OTP generator (default length: 6)
const otpGenerator = OtpKit.create("random", { length: 6, charset: "numeric" });

const otp = otpGenerator.generate();
console.log(otp) # "879053"

# Verify OTP (with optional expiry)
const isValid = otpGenerator.verify("123456", otp, { expiresAt: Date.now() + 30000 });
console.log("Is OTP valid?", isValid); 

⚙️ Options

RandomOtpOptions

| Option | Type | Default | Description | |----------------|----------------------------------------------------|----------|--------------------------------------------------| | length | number | 6 | Length of the OTP | | charset | "numeric" \| "alphabetic" \| "alphanumeric" \| "custom" | "numeric" | Defines which characters can be used in OTP | | customCharset| string | undefined | Required when charset = "custom" |

Charset Modes

| Mode | Characters Allowed | Example OTP | |---------------|-------------------------|---------------| | numeric | 0-9 | 483920 | | alphabetic | a-zA-Z | AbCdEf | | alphanumeric| 0-9a-zA-Z | a9B3c2 | | custom | User-defined characters | ABCDE |

✅ Example with custom charset:

const otpGenerator = OtpKit.create("random", {
  length: 5,
  charset: "custom",
  customCharset: "ABCDE"
  });
console.log(otpGenerator.generate()); // Example output: BCAAD

📄 License

MIT