Some are online, but encrypted, with options to export the passwords in case the service goes down.
“Why should I trust them?”
Well, the software is open source, and regularly audited by people using it. Many password managers, such as Bitwarden (not sponsored, although I’d like to get a sponsorship) uses end-to-end encryption to secure the passwords so someone hacking the servers or a rogue employee can’t access anything, It would just look like random noise. You don’t have to know coding, you just have to trust that someone in the world will have the knowledge to inspect the code and report any suspicious code. Just regularly back up the passwords to a local file so you still have them in case they shut down.
Trying to remember passwords made me constantly stressed trying to remember them. A password made life much easier. Better than a single point of failure like your brain. One password is much easier to remember, and that one password can be as complex as you want, because that’s the only one you’d have to worry about.
Sincerely,
Someone who’s depressed af and constantly forget passwords