README.md

OTP Service

The OTP (One-Time Password) Free Service is a Node.js-based service that allows you to generate and verify one-time passwords (OTP) via email. This service is useful for adding an extra layer of security to your applications by enabling two-factor authentication (2FA) or passwordless login.

Demo

• API: otp-service-beta.vercel.app
• App: otp-service-app.vercel.app

Table of Contents

• Features
• Getting Started
  • Prerequisites
  • Installation
• Usage
  • Generating an OTP
  • Verifying an OTP
• Configuration
  • Environment Variables
• Scheduled OTP Cleanup
• Spam Detection
• Donation
• License

Features

Feature	Description
Generate numeric, alphanumeric, or alphabet based OTPs	Generate one-time passwords with various character types: numeric, alphanumeric, or alphabet based.
Send OTPs via email	Send OTPs to users via email for authentication or verification.
Verify OTPs for user authentication	Verify OTPs provided by users for secure authentication.
Automatic cleanup of expired OTPs	Automatically remove expired OTPs from the database based on a configured cron schedule.
Spam detection	Detect spam requests and block them from being processed.
Customizable OTP validity period and size	Adjust the validity period and size (length) of OTPs to match your security requirements.
Rate limiting for OTP generation	Implement rate limiting to prevent abuse and ensure the service is used responsibly.
Multiple email service providers supported	Choose from multiple email service providers (e.g., Gmail, Outlook) to send OTP emails.
Flexible configuration via environment variables	Customize the service's behavior by configuring environment variables.
Easy-to-use API with JSON input/output	Interact with the service through a user-friendly JSON API for OTP generation and verification.

Getting Started

Prerequisites

Before you begin, ensure you have met the following requirements:

Prerequisite	Description
Node.js and npm	Install Node.js and npm on your development machine.
MongoDB database	Set up a MongoDB database (local or cloud-hosted, e.g., MongoDB Atlas) for storing OTP data.

Installation

1. Clone the repository:

   git clone https://github.com/sauravhathi/otp-service.git

2. Navigate to the project directory:

   cd otp-service

3. Install the dependencies:

   npm install

4. Configure your environment variables by creating a .env file in the project root directory. You can use the provided .env.example as a template.

5. Start the service:

   npm start

The service should now be running on the specified port (default is 3000).

Usage

Generating an OTP

To generate an OTP for a user, make a POST request to the /api/otp/generate endpoint with the user's email address in the request body. You can also specify the OTP type, organization name, and email subject.

Example request:

POST /api/otp/generate
{
  "email": "user@example.com",
  "type": "numeric",
  "organization": "MyApp",
  "subject": "OTP Verification"
}

The service will send an email containing the OTP to the user's email address.

Verifying an OTP

To verify an OTP for user authentication, make a POST request to the /api/otp/verify endpoint with the user's email address and the OTP in the request body.

Example request:

POST /api/otp/verify
{
  "email": "user@example.com",
  "otp": "123456"
}

The service will respond with a success message if the OTP is valid.

Configuration

You can customize the OTP service by modifying the environment variables in the .env file. Here are some key configuration options:

Environment Variables

Variable	Description
PORT	The port on which the service listens.
MONGODB_URI	The MongoDB connection string.
OTP_VALIDITY_PERIOD_MINUTES	The validity period of OTPs in minutes.
OTP_SIZE	The size (length) of OTPs.
CRON_SCHEDULE	The cron schedule for OTP cleanup.
ALLOWED_DOMAINS	Comma-separated list of allowed email domains.
GMAIL_USER	Gmail username (used for sending emails).
GMAIL_PASS	Gmail password (used for sending emails).
BLOCK_KEYWORDS_RULES	Comma-separated list of blocked keywords.

Scheduled OTP Cleanup

The service automatically clears expired OTPs based on the configured cron schedule. By default, it runs daily at midnight to remove expired OTPs.

Spam Detection

The service uses a spam detection mechanism to prevent abuse. It checks the request body for spam keywords and blocks the request if any are found. You can configure the spam keywords by setting the SPAM_WORDS environment variable.

Donation

If you find this project useful and want to support its development, consider buying us a coffee! Your support is greatly appreciated.

Donate: saurav.34@paytm

License

This project is licensed under the MIT License. See the LICENSE file for details.