This is the password manager I use. Code safely runs only in the browser.
Python and Android versions are also available.
No dependencies on any other party, this makes for a very safe password manager. Everytime the same strong password gets created based on your master password and a keyword (such as reddit or github).When a website wants you to create a new password: just increment (e.g. reddit1, reddit2). Easy.
It will take 1 million macbook pros 1e19 years to find the password when it would be found at half of the possible time.