What is OTP?

A one-time password (OTP) is an auto-generated numeric or alphanumeric string of characters useful as a single-use password that authenticates a transaction or login. 

Each and every password of this kind is unique and usually has a usability period, after which it expires and cannot be used any longer. 

In general, an OTP is lauded as a more viable and secure password than user-created passwords. It adds an extra layer of security that ensures account information cannot be compromised. 

How are OTPs generated? 

There are a couple of ways OTPs are generated and sent to the user. 

Hardware tokens refer to passwords being sent to the user through a physical device such as a security token device. 

Software tokens refer to passwords being sent to the user’s handheld device, such as their mobile phone. This process is generally undertaken through the use of the Short Message Service (SMS). 

In OTP-based authentication methods, the OTP and the server rely on shared secrets. The unique characters are generated by the Hashed Message Authentication Code (HMAC) algorithm. 

The OTP values are time-stamped for greater security, which is why this option is preferred in high-risk transactions or logins. 

OTPs can be delivered to users through several avenues, such as text messages, emails, or via a dedicated mobile application. 

Here Are The Top OTP Service Providers At The Moment:

SMSCountry 

We cannot help but start off this list with our very own product, SMSCountry.

Via SMSCountry, Telebu extends its SMS services to over 550 networks in over 200+ countries. 

Some of the services we offer range from bulk SMSing, API Integration, voice SMS, email to SMS, and OTP services. 

SMSCountry allows users to send their OTPs with unique sender IDs for better recognition by the recipient. 

External Ecommerce plug-ins can also be integrated into the software such as Zen Cart, CS-Cart, BigCommerce, etc. 

TeleSign 

Source: Mobile Industry Review 

TeleSign is a company that mainly focuses on two-factor authentication services. They primarily work with social media websites that allow users to have added security to their accounts. 

They offer patented phone-based verification and two-factor authentication. These services are undertaken using time-based, one-time passcodes sent as SMSes or voice messages. 

Other than being one of the best OTP Service Providers, TeleSign also offers Digital Identity and Programmable Communication services that range from PhoneID, Integratable voice calling in apps, and Rich Communication Services (RCS).

2Factor 

Source: Invest In Startups 

2Factor (by Solv Technologies) is a cloud mobile messaging platform that uses A2P messaging services. They develop their services in-house. Their specialities are namely A2P SMSing, 2-Factor Authentication, and Telecommunications APIs. 

Their OTP services are offered as text-based or voice-based services. Real-time reports are also available for users as and when the SMSes are sent out. 

Exotel

Exotel offers cloud telephony services at an enterprise level. One of its products, nOTPTM, includes OTP services. 

This particular service offers two-factor authentication, passwordless logins, resetting of passwords, and spam prevention. 

This service allows users to authenticate and verify their transactions and logins without the need for third parties. 

Exotel extends its services all over India and Southeast Asia. 

Msg91 

Msg91 was founded in 2008 and is under the parent company, Walkover Technologies. They offer cloud communication platform services. 

Focusing on messaging solutions and business communications, they mainly deal with SMS, Email, Voice, WhatsApp, and RCS via API.

SendOTP is Msg91’s 2Factor Authentication product that has OTP features. 

Their services span from 800 networks in 190 countries. 

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Read our other blog: Top 10 Bulk SMS Service Providers in the Market