Most of the time cache memory or database used to verify OTP. It's expensive operation. We can verify OTP without using database or cache memory.
Today I will explain how to verify OTP without cache memory/ database operation.
OTP requested user send request with mobile number. Then requested number, generated OTP(using otp-generator) is used to create hash value using sha256. Then hash value is used for OTP request response & preserve it on frontend. Generated OTP will send to requested users Mobile number.
After getting OTP, user now verify OTP with 2nd request. On the 2nd request OTP, Mobile No & Hash will be sent to the server to verify. Using mobile no & OTP we will generate new hash. New hash value will be compared with requested hash value. If both hash value matched then OTP is verified.