(often distributed as "Zappy Checker.rar" ) is a third-party automated "account checker" or "cracking" tool typically used to validate large lists of stolen login credentials (email/password pairs) against specific online services.
Support for running hundreds of simultaneous login attempts to process large lists quickly. Zappy Checker.rar
Using account checkers to access accounts you do not own is illegal and constitutes a "credential stuffing" attack. (often distributed as "Zappy Checker