CloudOTP - One-Time Password SMS Verification Service
Secure your application with one-time passwords delivered via SMS. CloudOTP generates, delivers, and validates OTP codes automatically - so you can add verification without building the infrastructure yourself.
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What is a One-Time Password?
A one-time password (OTP) is a unique verification code generated for a single authentication session. Unlike static passwords, OTPs expire after one use or a short time window - typically 30 to 60 seconds - making them resistant to replay attacks and credential theft.
OTP verification via SMS is the most widely adopted security method because it requires no app installation from end users. They receive a code on their phone, enter it, and they're verified.
CloudOTP is a one-time password generator that creates, delivers, and validates verification codes via SMS - all through a single API integration.
OTP Generator - How CloudOTP Works
API Request
Your app calls the CloudOTP API when a user needs verification.
Code Generation
We generate a cryptographically random, single-use code tied to that request.
SMS Delivery
OTP delivered to the user's phone in under 3 seconds via our multi-carrier network.
User Enters Code
User receives the SMS and types the code into your application.
Validation
Your app verifies the code via API. Pass/fail response in milliseconds.
OTP Use Cases
Why Teams Choose CloudOTP
| Feature | Detail |
|---|---|
| Delivery Speed | Sub-3-second SMS delivery |
| Deliverability | 99.9% success rate across US & Canadian carriers |
| Integration | REST API + SDKs (Node.js, Python, PHP) |
| Code Generation | Automatic - no need to build your own logic |
| Validation | Built-in - single API call to verify |
| Compliance | 10DLC registered, carrier-approved |
| Expiration | Configurable TTL (30s, 60s, 5min) |
| Scalability | From 10 OTPs/day to 1M+/day |
OTP API Quick Start
Add SMS verification to your application in minutes:
# Request an OTP code be sent to a phone number curl -X POST https://api.cloudcontactai.com/otp/send \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "phone_number": "+14155551234", "expiration_seconds": 60 }'
{
"status": "sent",
"otp_id": "otp_8f3k2j1",
"expires_at": "2026-07-21T14:31:40Z"
}
# Validate the code entered by the user curl -X POST https://api.cloudcontactai.com/otp/verify \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "otp_id": "otp_8f3k2j1", "code": "847291" }'
OTP vs. Other Verification Methods
| Method | Pros | Cons |
|---|---|---|
| SMS OTP (CloudOTP) | No app install, universal device support, familiar UX | Requires phone number |
| Authenticator Apps | No network dependency, works offline | Requires app install, user friction |
| Email OTP | Works without phone number | Slower delivery, often missed in spam |
| Hardware Tokens | Highest security | Expensive, easy to lose |
Security & Compliance
Pricing
OTP messages are billed at standard SMS rates. No additional per-verification fees.
Pay-as-you-go - No minimums, no contracts
Volume discounts - Available for 100K+ verifications/month
Free trial - 50 free OTP messages to test the integration
Add OTP Verification to Your App Today
No credit card required. Start sending verification codes in minutes.
Try CloudOTP Free →