Hello,
I have good working experience in C#. I have worked on a similar task.
Refer : https://www.freelancer.com/jobs/Software-Architecture/automation-software/
The approach I am planning to follow:
Input .txt/any file has list of accounts in given format. Read the account credentails. Try logging in to the site. If login fails then account is invalid, valid ortherwise
Please contact me.
Thanks,
Ramya