A password manager that doesn't store any passwords, only their salts. Site
Lesser Pass can't store passwords for you, but instead generates secure passwords. Every password requires: an account, a username, a desired password length, and an index. If your password is leaked, changing the index is an easy way to force Lesser Pass to generate a completely new password, however changing the account or username will do the same thing. The notes field does not affect generated passwords in any way and is simply a convenience.
After logging in with a google account, enter a master password, and add some new password info. Clicking on a row will generate a password and copy it to your clipboard. Your master password is never saved, and the input field is cleared after 5 minutes.
Lesser Pass leverages Web Crypto to generate passwords using 250000 rounds of PBKDF2 SHA-256. The relevent code is in this file. Generated passwords can contain all 95 ASCII printable characters.
Full credit for this idea goes to LessPass, and the Web Crypto code was adapted from their repo. The algorithm for converting from binary to base n was adapted from this project.
Why not use a key lengthening function, plug the result into a symmetric algo, then use that to en/decrypt passwords (so you could choose your own passwords)? Good question.