Verify API Technical Details

The Verify API is Vonage’s next-generation two-factor authentication (2FA) solution. It expands on traditional authentication methods by supporting a wider range of channels, including over-the-top (OTT) channels like WhatsApp, as well as SMS, Voice, and Email.

Verify introduces event callbacks and summary callbacks that enable deeper integrations and greater customization. For example:

  • You can configure a webhook to receive summary callbacks, providing detailed insights into which channels successfully converted and which ones did not.
  • Event callbacks enable advanced user experiences, such as the WhatsApp Codeless flow. In this case, an end-user can simply tap a button within a WhatsApp message to authenticate, triggering an event callback to your backend to continue the verification flow.

Authentication

Verify requires that you authenticate API requests securely. Learn more about how to authenticate your Verify API requests in the Authentication Guide.

Workflow

The workflow defines the sequence of channels used to deliver the OTP to the end-user. You can customize the order, timeout settings, and fallback behavior to optimize the verification experience.

Find detailed information and examples in the Workflow Guide.

How does the API work?

Below is a visual representation of a Verify request flow with summary callbacks:

Verify V2 Request with Summary Callbacks

For initial setup and a step-by-step introduction, please refer to the Getting Started Guide.

Supported Languages

The Verify API supports many languages with the locale parameter (see API Reference). The Verify locale guide contains a list of supported locale.

What's next?

Now that you understand the technical foundations of the Verify API, you're ready to start building!

  • Follow the Getting Started Guide to implement your first verification workflow step-by-step.

  • Explore the API Reference for a complete list of endpoints, parameters, and advanced options.