Here is a list of 20 OTP SMS provider services with details about their offerings:
1. Twilio: Twilio is a cloud communications platform that provides APIs for sending and receiving SMS, voice, and video messages. Their SMS API allows you to send OTP SMS messages to your users. Twilio offers a free trial account with a limited number of SMS messages.
2. Nexmo: Nexmo is a cloud communications platform that provides APIs for sending and receiving SMS, voice, and video messages. Their SMS API allows you to send OTP SMS messages to your users. Nexmo offers a free trial account with a limited number of SMS messages.
3. Textlocal: Textlocal is an SMS marketing platform that also offers an OTP SMS API. Their API allows you to send OTP SMS messages to your users. Textlocal offers a free trial account with a limited number of SMS messages.
4. MSG91: MSG91 is a cloud communications platform that provides APIs for sending and receiving SMS, voice, and video messages. Their SMS API allows you to send OTP SMS messages to your users. MSG91 provides a free demo account for testing their service.
5. Plivo: Plivo is a cloud communications platform that provides APIs for sending and receiving SMS, voice, and video messages. Their SMS API allows you to send OTP SMS messages to your users. Plivo offers a free trial account with a limited number of SMS messages.
6. Vonage: Vonage is a cloud communications platform that provides APIs for sending and receiving SMS, voice, and video messages. Their SMS API allows you to send OTP SMS messages to your users. Vonage provides a free trial account with a limited number of SMS messages.
7. Amazon SNS: Amazon Simple Notification Service (SNS) is a messaging service provided by Amazon Web Services (AWS). It allows you to send push notifications and SMS messages to mobile devices. You can use Amazon SNS to send OTP SMS messages. AWS offers a free usage tier that includes a limited number of SMS messages.
8. Firebase Cloud Messaging: Firebase Cloud Messaging (FCM) is a messaging platform provided by Google. It allows you to send push notifications and SMS messages to mobile devices. You can use FCM to send OTP SMS messages.
9. Sinch: Sinch is a cloud communications platform that provides APIs for sending and receiving SMS, voice, and video messages. Their SMS API allows you to send OTP SMS messages to your users. Sinch offers a free trial account with a limited number of SMS messages.
10. MSGClub: MSGClub is a cloud communications platform that provides APIs for sending and receiving SMS messages. Their SMS API allows you to send OTP SMS messages to your users. MSGClub provides a free demo account for testing their service.
11. Fast2SMS: Fast2SMS is an SMS marketing platform that also offers an OTP SMS API. Their API allows you to send OTP SMS messages to your users. Fast2SMS provides a free trial account with a limited number of SMS messages.
12. MySmsMantra: MySmsMantra is an SMS marketing platform that also offers an OTP SMS API. Their API allows you to send OTP SMS messages to your users. MySmsMantra provides a free demo account for testing their service.
13. Karix.io: Karix.io is a cloud communications platform that provides APIs for sending and receiving SMS messages. Their SMS API allows you to send OTP SMS messages to your users. Karix.io provides a free trial account with a limited number of SMS messages.
14. Mobily.ws: Mobily.ws is a cloud communications platform that provides APIs for sending and receiving SMS messages. Their SMS API allows you to send OTP SMS messages to your users. Mobily.ws provides a free demo account for testing their service.
15. Clickatell: Clickatell is a cloud communications platform that provides APIs for sending and receiving SMS messages. Their SMS API allows you to send OTP SMS messages to your users. Clickatell offers a free trial account with a limited number of SMS messages.
16. Gupshup: Gupshup is a cloud messaging platform that provides APIs for sending and receiving SMS and chat messages. Their SMS API allows you to send OTP SMS messages to your users. Gupshup offers a free trial account with a limited number of SMS messages.
17. Route Mobile: Route Mobile is a cloud communications platform that provides APIs for sending and receiving SMS messages. Their SMS API allows you to send OTP SMS messages to your users. Route Mobile provides a free trial account with a limited number of SMS messages.
18. InfoBip: InfoBip is a cloud communications platform that provides APIs for sending and receiving SMS, voice, and chat messages. Their SMS API allows you to send OTP SMS messages to your users. InfoBip offers a free trial account with a limited number of SMS messages.
19. Kaleyra: Kaleyra is a cloud communications platform that provides APIs for sending and receiving SMS messages. Their SMS API allows you to send OTP SMS messages to your users. Kaleyra provides a free trial account with a limited number of SMS messages.
20. BulkSMS: BulkSMS is an SMS marketing platform that also offers an OTP SMS API. Their API allows you to send OTP SMS messages to your users. BulkSMS provides a free trial account with a limited number of SMS messages.
It’s important to note that the free trial accounts and free usage tiers offered by these OTP SMS provider services may have limitations and restrictions. You should carefully review the terms and conditions of each service to ensure that it meets your specific requirements. Additionally, you should ensure that any service you use to send OTP SMS messages complies with applicable regulations, such as GDPR or CCPA, depending on your location.