Last I checked, there were some third party iOS apps but the Bitwarden iOS app was far superior.

I have found KeePassium to be an excellent iOS KeePass client.

Strongbox is good on both iOS and macOS...

KeePass only officially works on Windows. All non-Windows versions are unofficial versions. See [1] for a list.

[1] https://keepass.info/download.html

There's also KeePassX and KeePassXC which have been working fine on Linux for years.

- https://keepassxc.org/

Not to mention mobile clients even on Sailfish OS.

KyPass has been excellent for me for the last several years.

1Password is by far the best on iOS, and it works on Mac, PC, Linux, and Android as well.