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OTP / 2FA

Verify users
in seconds.
Across every channel.

Send, verify, and expire one-time passwords via SMS or voice — with automatic fallback, tamper-proof tokens, and a one-line verify call.

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No setup fees
SMS + Voice channels
Tamper-proof tokens
~110ms delivery

99.7%

Delivery rate

~110ms

Avg. delivery

91.3%

Verify rate

10+

African countries

99.9%

Uptime SLA

2 calls

Send + verify

How it works

Two API calls.
Full verification flow.

01

Send the OTP

Call sendexa.otp.send() with a phone number and channel. We generate a cryptographically secure code, dispatch it immediately, and return a request ID.

await sendexa.otp.send({
  to: "+233551234567",
  channel: "sms",
  expiry: 300
});
02

User enters the code

Your UI collects the 4–8 digit OTP from the user. No need to store the code server-side — we handle that for you, including expiry and attempt limits.

// Your UI collects:
// [ 4 ][ 8 ][ 2 ][ 9 ][ 1 ][ 0 ]
03

Verify in one call

Pass the request ID and user-entered code to sendexa.otp.verify(). Get a boolean result — verified or rejected. We track failed attempts automatically.

await sendexa.otp.verify({
  request_id: "otp_abc123",
  code: "482910"
}); // → { valid: true }

What's included

Everything you need
to verify with confidence.

SMS OTP

Deliver 4–8 digit codes via SMS in under 200ms. DND-aware routing ensures transactional codes always arrive, even on restricted numbers.

DND bypassPriority queueCustom length

Voice OTP

Fall back to voice calls automatically when SMS fails or for users who prefer audio. Text-to-speech reads the code in the user's local language.

Auto-fallbackLocal languagesRepeat reading

Smart Fallback

Define a channel waterfall: try SMS first, then WhatsApp, then voice. Sendexa retries automatically based on your configured priority order.

SMS → VoiceSMS → WhatsAppCustom order

Token Management

We handle code generation, expiry, and attempt limits server-side. No token storage in your DB — just request IDs. Tokens are single-use by default.

Single-useConfigurable expiryAttempt limits

Fraud Detection

Rate limiting, velocity checks, and disposable number detection prevent OTP abuse before it hits your account balance or your users.

Rate limitingVelocity checksDisposable number filter

Webhook Events

Receive real-time events for every OTP lifecycle step — sent, delivered, opened, verified, expired, and failed — streamed to your endpoint.

Real-time eventsRetry with backoffSigned payloads

Developer experience

Verify users in
two API calls.

SDKs for Node.js, Python, PHP, and cURL. No token storage on your end — just send a code, then verify it. We handle expiry, retries, and attempt limits.

01

Call otp.send() with a phone number

02

User enters the code in your UI

03

Call otp.verify() — get a boolean back

import Sendexa from "sendexa";

const client = new Sendexa(process.env.SENDEXA_API_KEY);

// 1. Send OTP
const { request_id } = await client.otp.send({
  to: "+233 55 123 4567",
  channel: "sms",          // "sms" | "voice"
  expiry: 300,             // seconds
  length: 6,               // digits
  brand: "MyApp",          // appears in message body
});

// 2. Verify when user submits
const result = await client.otp.verify({
  request_id,
  code: "482910",          // from user input
});

if (result.valid) {
  // ✓ authenticated
} else {
  // ✗ invalid or expired
  console.log(result.reason); // "wrong_code" | "expired" | "too_many_attempts"
}

Use cases

Secure every
user touchpoint.

🔑

Login & 2FA

  • Phone number login
  • Step-up authentication
  • Account recovery
  • Session verification
💳

Payments

  • Transaction confirmation
  • Card verification
  • High-value transfer auth
  • Payout confirmation
🛂

KYC & Onboarding

  • Phone number ownership
  • Identity verification
  • Consent confirmation
  • Age verification
🔒

Account Changes

  • Email / phone update
  • Password reset
  • Profile changes
  • Device registration
Start building today — it's free

Your first 1,000 OTPs
are on us.

Sign up, get your API key, and send your first OTP in under 5 minutes. No credit card required.

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No credit card required1,000 free OTPs includedSMS + Voice channelsCancel anytime