have i been pwned? - Check if your account has been compromised in a data breach
LeakCheck - Data breach search engine, low price starting from $10/mo, one email address for free, unlimited API, 7B+ entries
DeHashed - DeHashed is the largest & fastest data breach search engine.
Profil3r - The Dead Frontier Profiler : Full of useful information for boss hunting, looting, and enjoying Dead Frontier, the zombie MMO.
BreachDirectory.org - BreachDirectory.org allows you to search through all public data breaches to make sure your emails, usernames, passwords, and domains haven't been compromised.
Firefox Monitor - Firefox Monitor arms you with tools to keep your personal information safe.