Use Case
OTP Delivery for Login and User Verification
Send an OTP using an approved authentication template and track delivery through an Alert21 Message ID. When Alert21 Verify launches, applications can move OTP generation and verification state into a dedicated verification API.
SMS OTP Flow Today
- Your application generates the OTP securely.
- Your server calls the Alert21 SMS API with the approved template ID.
- Alert21 validates and routes the message.
- Your application verifies the OTP with its own server-side logic.
- Delivery status remains available independently of the authentication decision.
OTP Security Practices
- Short expiry.
- Attempt limits.
- Resend throttling.
- No OTP values in analytics or ordinary logs.
- Bind OTP to a specific verification transaction.
- Prevent replay.
- Rate-limit by recipient and account.
EVERY ALERT. ONE API.
Turn your next business event into a traceable alert.
Start with DLT-ready SMS today on Alert21’s developer-first communication platform.