NeoAtlantis Slate by NeoAtlantis

This addon generates "password-request-url"s for your later use, and reads them to give an actual password. These urls are intended to be stored in your existing password managing software (like Keepass, or any online services, but even a Notepad txt file will work!) in replace of actual passwords.

In case your password manager compromises, attackers cannot utilize these urls unless they also gain access to this addon (precisely, a running version with memory dump, and certainly the seedfile & your password for initialization). This addon is designed such that the working crypto keys will not be extractable (cannot be copied, viewed or exported) under normal circumstances. Thus it behaves like an additional authentication factor and enhances online password security.