Pete Inbox Cleaner is a personal tool for one mailbox. It is operated by Peter Gallo, and it is not offered to the public.
The tool reads the Spam and Promotions mail in that mailbox. It keeps messages from addresses and domains on a private keep list. It moves the rest of that Spam and Promotions mail to Gmail Trash. It does not permanently delete mail. Gmail empties Trash on its own schedule, about 30 days later.
It does not send mail. It does not unsubscribe from lists. It does not read a second Google account. This website does not sign anyone in, and it does not store mailbox data.
Google user data is used only to run that cleanup for the mailbox owner. It is not sold, not used for advertising, and not shared with anyone else.