Mozilla is launching Firefox Monitor, a free service that notifies people when they've been part of a data breach.
In order to use the service, visit monitor.firefox.com and type in your email address. Through our partnership with Troy Hunt's "Have I Been Pwned," your email address will be scanned against a database that serves as a library of data breaches. The service will let you know if your email address and/or personal info was involved in a publicly known past data breach. Once you know where your email address was compromised you should change your password and any other place where you've used that password.