> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dojah.io/llms.txt
> Use this file to discover all available pages before exploring further.

# OTP Authentication API

> Send and verify one-time passwords by SMS. Use for login, 2FA, and transaction confirmation with one API.

Authenticate users securely using Dojah’s OTP service.
This API enables you to send time-bound one-time passwords to users’ phone numbers,
then validate the code when they submit it. It’s ideal for login, signup,
transaction confirmation, and two-factor authentication (2FA).

***

#### How It Works

The OTP process is straightforward:

1. **Send OTP**\
   Make a POST request to the `send-otp` [endpoint](/docs/messaging/send-otp) with the user’s phone number. A 6-digit code is generated and sent via SMS using your registered Sender ID.

2. **User Inputs OTP**\
   The user enters the code they received.

3. **Validate OTP**\
   Make a POST request to the `validate-otp` [endpoint](/docs/messaging/validate-otp) with the phone number and the code. If valid and not expired, you’ll receive a success response.

Each OTP is valid for a limited time and can only be used once. You can also set your preferred OTP expiration time and resend behavior.

#### Use Cases

* Secure user login or account creation
* Authorize wallet top-ups, withdrawals, or payments
* Confirm sensitive changes (e.g., password updates, PIN resets)
* Add an extra layer of verification during onboarding

#### Why Use Dojah OTP

* Fast, telco-optimized delivery
* Custom sender ID branding
* Developer-friendly endpoints
* Built-in expiration and retry logic
* Secure and stateless validation