Looking for a plugin

Hi everyone. I am looking for a plugin (if such thing exists) that can do what I need on my website, so if anyone knows about something like this (either free or paid) please share.
Basically I need something like a promo code system, or voucher system – the user would access a page with a simple form where he would input a code. That code must match one of the codes that should be stored in “the back”. If it does, he would get a confirmation message or something. If not, an error.
I tried to create something like this with form builders and conditional logic, but you can imagine how much time would be needed to manually add thousands of codes as conditions for that field…

Thank you!