OTP API for
Crypto Exchanges
Verify Vietnamese users on your exchange without Twilio or Vonage flagging your account. Crypto-prepaid, no KYC, $0.022 per delivered OTP.
Pain points crypto-exchange teams hit
Mainstream SMS providers ban crypto accounts on sight
Twilio and Vonage compliance scan message bodies for "exchange", "wallet", "trading" — your account gets a 48-72h suspension that breaks production. Even after appeal, you stay flagged.
Card billing creates chargeback risk
Crypto-related charges on company cards trigger fraud reviews. Switching to wire transfer slows top-up to days. We bill in USDT/USDC — settlement in minutes, no chargeback path.
Withdrawal confirmation needs <30s OTP delivery
Users abandon withdrawals if the code does not arrive fast. Vietnamese carrier latency varies wildly per provider. We optimize for sub-15s voice delivery across Viettel / Vinaphone.
Why NEXO ROUTE fits
- No vertical restriction — sign up and send within minutes
- Pay in stablecoins, settle in one block confirmation
- Webhook-driven status: charge only when code reaches the user
- Voice OTP option for users with SMS blocking enabled
- Per-carrier routing: Viettel + Vinaphone + Vietnamobile (voice/SMS), Mobifone (SMS-only)
Integration approach
Trigger send on user-initiated actions (login, withdraw, settings change). Generate the 6-digit code in your auth service, persist hashed, send via our API. Verify against the hash on user submission.
Sample · TypeScript
// On withdrawal request
const code = generateOtp(6);
await redis.setex(`otp:withdraw:${userId}`, 300, await hash(code));
const res = await fetch('https://nexoroute.dev/api/v1/send-otp', {
method: 'POST',
headers: {
'Authorization': `Bearer ${process.env.NEXO_KEY}`,
'Content-Type': 'application/json'
},
body: JSON.stringify({ phone: user.phone, code })
});
const data = await res.json();
if (!data.ok) {
// insufficient_balance, invalid_phone, no_route — see docs
throw new Error(data.error);
}
return { deliveryId: data.id, carrier: data.carrier };FAQ
Will you suspend my account if you find out we run a crypto exchange?
No. We are built for gray-area verticals — crypto, Web3, gambling, adult — that mainstream providers refuse. Our terms explicitly allow these use cases.
What is the typical OTP delivery time for withdrawal confirmation flows?
Voice OTPs through Viettel / Vinaphone typically ring within 5-10s. SMS via Mobifone takes 15-45s depending on carrier load. Failed sends are refunded.
Can I trigger 1000 OTPs in 1 second during a market event?
Yes, but TKC upstream rate-limits 1 call / 30s per unique phone. Different users in parallel = no rate limit on your end. For burst traffic, contact us in advance.
Do you have an SLA?
No paid SLA — we publish 90% delivery target measured monthly. Real-time delivery stats are on your dashboard.
Built for crypto exchanges
5 free test OTPs on signup. No card, no KYC, no vertical review.