Introduction
Have you ever logged in to an application using a one-time password (OTP) sent to your mobile number or email address? OTP verification is a common security feature used by banking applications, e-commerce websites, payment systems, and many other online services.
Behind this simple process, an API works to generate, send, verify, and sometimes expire the OTP.
But what happens if the OTP is incorrect? What if it expires? Can a user verify the same OTP multiple times? What if someone requests too many OTPs in a short period?
These are important questions for a software tester.
In this guide, you will learn how to test an OTP API, which test cases to cover, how to validate API responses using Postman, and what security checks QA engineers should perform.