OTP SMS API —
Sub-1-Second Verification at Scale
Enterprise OTP SMS API for account verification, login authentication and 2FA. Direct SS7 carrier connections deliver one-time passwords in under 1 second on average. Built-in fraud detection, automatic retry logic and voice OTP fallback. 190+ countries.
OTP SMS API • OTP verification API • one-time password SMS • 2FA SMS API • SMS verification API • phone number verification API • OTP gateway • OTP SMS UAE • OTP SMS India • SMS based authentication
Send Your First OTP in 3 Lines of Code
RESTful API with SDKs for PHP, Python, Node.js, Java, Ruby and .NET. Postman collection included. Sandbox environment for testing.
const response = await fetch('https://api.bulksmshub.com/v1/otp/send', {
method: 'POST',
headers: { 'Authorization': 'Bearer YOUR_API_KEY' },
body: JSON.stringify({
phone: '+971585527099',
channel: 'sms', // or 'whatsapp', 'voice'
template: 'Your code is {code}'
})
});
Built for Developers
Simple JSON request/response. No SDK required to get started.
PHP, Python, Node.js, Java, Ruby, .NET — install via package manager.
Real-time delivery status callbacks. Know instantly if an OTP was delivered.
Built-in code verification endpoint — no need to build your own validation logic.
OTP Verification Flow in 4 Steps
Built for Mission-Critical Authentication
Sub-1-Second Delivery
Direct SS7 carrier connections in UAE, Saudi Arabia, India and 190+ countries deliver OTPs in 600ms–1.5s average — critical for conversion-sensitive signup and login flows.
Built-In Fraud Detection
Automatic rate limiting, velocity checks and suspicious pattern detection prevent OTP pumping fraud and toll fraud attacks that drain your SMS budget.
Smart Retry & Fallback Logic
Configurable retry attempts, automatic fallback to voice call OTP if SMS fails, and WhatsApp OTP as an alternate channel — maximise verification completion rates.
WhatsApp OTP Available
Send OTP via WhatsApp Business API as a cost-effective alternative or fallback channel. Same verify endpoint works across SMS, WhatsApp and voice.
Real-Time Delivery Analytics
Live dashboard showing delivery rates, verification completion rates, average delivery time by country and carrier-level performance breakdowns.
190+ Country Coverage
Single API endpoint handles global OTP delivery with automatic local compliance — DLT routing for India, TDRA for UAE, sender ID management per market.
OTP Delivery Speed by Country
| Country | Avg Delivery | Success Rate | Direct Carriers |
|---|---|---|---|
| 🇦🇪 UAE | 680ms | 99.97% | Etisalat, du |
| 🇸🇦 Saudi Arabia | 760ms | 99.9% | STC, Mobily, Zain |
| 🇮🇳 India | 920ms | 99.5% | Jio, Airtel, Vi, BSNL |
| 🇶🇦 Qatar | 750ms | 99.9% | Ooredoo, Vodafone |
| 🇬🇧 UK | 1.1s | 99.6% | EE, O2, Vodafone, Three |
| 🇺🇸 USA | 1.2s | 99.3% | AT&T, Verizon, T-Mobile |
| 🇪🇬 Egypt | 1.0s | 99.3% | Vodafone, Orange, Etisalat, WE |
| 🇧🇷 Brazil | 1.3s | 99.1% | Claro, Vivo, TIM, Oi |
Simple, Transparent OTP Pricing
- REST API access
- Sandbox environment
- Webhook delivery receipts
- Email support
- Everything in Starter
- WhatsApp + Voice OTP fallback
- Fraud detection enabled
- Priority routing
- 30-min support SLA
- Everything in Pro
- Dedicated account manager
- 99.95% uptime SLA
- Custom retry logic
- Direct SMSC connections
- Custom SLA 99.99%
- White-label option
- 24/7 phone support
OTP SMS API — Frequently Asked Questions
What is an OTP SMS API?
An OTP SMS API is a programmatic interface that lets developers send one-time passwords via SMS for account verification, login authentication and two-factor authentication. BulkSMSHub's OTP API delivers codes via direct SS7 carrier connections in under 1 second on average, with built-in retry logic, fraud detection and global coverage across 190+ countries.
How fast is OTP SMS delivery?
BulkSMSHub OTP SMS delivers in 600ms–1.5s average via direct SS7 carrier routes, depending on destination country. UAE: 680ms. Saudi Arabia: 760ms. India: 920ms. This compares to 2–5 seconds for OTPs sent via grey or indirect routes — a critical difference for signup conversion rates.
What is OTP pumping fraud and how do you prevent it?
OTP pumping fraud (also called toll fraud or SMS pumping) is when bad actors trigger massive volumes of OTP requests to premium-rate or international numbers, generating fraudulent telecom revenue at the business's expense. BulkSMSHub's OTP API includes automatic rate limiting per phone number, velocity-based anomaly detection and configurable daily spend caps to prevent this attack.
Can I send OTP via WhatsApp instead of SMS?
Yes. BulkSMSHub supports WhatsApp OTP delivery via the official WhatsApp Business API as both a primary channel and an automatic fallback if SMS delivery fails. The same /otp/verify endpoint works regardless of which channel (SMS, WhatsApp or voice call) delivered the code. See our WhatsApp pricing page for authentication category rates.
Do you offer voice call OTP as a fallback?
Yes. If SMS delivery is uncertain or fails (common in some emerging markets with carrier filtering issues), BulkSMSHub can automatically fall back to a voice call that reads the OTP code aloud. This significantly improves verification completion rates in markets with inconsistent SMS delivery.
What SDKs and integrations are available?
BulkSMSHub provides official SDKs for PHP, Python, Node.js, Java, Ruby and .NET. A full Postman collection is available for testing. Pre-built integrations exist for Firebase Auth, Auth0, Supabase and common authentication frameworks. View full API documentation →
Get Your OTP API Key — Free Trial
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Start Verifying Users in Minutes
Sub-1-second OTP delivery. 190+ countries. Free trial with sandbox API key — no credit card required.