We have implemented in our mobile application a rate limiting access after 5 failed attempts though a web based services (API). We lock down the account for 30 mins if the fives attempts have been performed.
My concern is about the customers who are using the app.. what if someone tried to run a script that will try to brute forcing and keep the lock the customers from using the application (30 mins).
Is there any solution than can be applied in this case.. as Captcha will not be because its an mobile application.