Password Leak Monitor от mathiscode

A browser addon that automatically monitors all passwords used and alerts you if it has been included in any data breaches.

How is this safe?

Your passwords are NEVER transmitted to any other system. This addon makes use of the haveibeenpwned API, which implements a k-Anonymity Model so your password can be checked without ever having to give your password to any other party.

How does it work?

It's a fairly simple extension: for every password you enter, a call is made to Have I Been Pwned with the first five characters of your hashed password. A list of potential matches is returned, and the addon determines if your hashed password matches any of the compromised hashes.