How to Integrate an OTP API into a Website or Mobile App

Adding phone verification is straightforward with the right flow. This article covers how to integrate an OTP API and the security details that matter.

Integrating an OTP API adds a verification layer to sign-up, login or payment. In essence, you call a provider API to send the code and manage generating, storing and checking the code on your server.

The basic flow

1. User requests a code → the server generates one and stores it with an expiry.
2. The server calls the provider API to send the SMS.
3. User enters the code → the server verifies and responds.
4. Limit retries and send frequency to prevent abuse.

Security details that matter

• Always generate and verify codes on the server, never the browser.
• Use short expiries (typically 60–300 seconds) and single-use codes.
• Rate-limit by phone number and IP.
• Never log OTP codes where they can be read.

Whether OTP is secure depends on how you handle it on the server, not on the message.

Waebox supports integration

Waebox Media provides an OTP API with documentation and integration support for your developers. Contact us for a sandbox.