LessPass

This add-on allows you to build LessPass passwords directly in your browser. LessPass is a password manager that guarantees you to generate the same password on the basis of unique information you provide. You can use LessPass to create passwords for various internet services (social networks , email, server passwords , ...). You can use this extension to generate complex password for your sites without the need to store them. You are the only one to know the information needed to generate a password. You can regenerate your passwords anywhere. No database, no sync needed. Tip: Use the keyboard shortcut Ctrl + Shift + L to launch LessPass

Screenshots from Chrome Web Store

Screenshots from Mozilla Add-ons