Closest to a password killer I've used so far is the built-in iCloud Keychain. My iPhone and MacBook both have access to the same passwords and most of the are randomly generated.
Ever watch security footage that overlooks people using iPhones? It's amazing how many sites display the plain-text password on the screen briefly even when using Keychain.
Additionally, iOS now integrates third-party password managers, so you get the same convenience with e.g. 1Password.