Choose a strong password from lists of randomly generated passwords, that has a length from 8 to 64 characters, for different applications.
Passwords for manual typing and use in trusted environment.
If you need a password, that can be typed in manually, you can use one of these 8 characters long passwords. They should only be used with another authorization method or in trusted environments.
Strong passwords for two factor authorization.
If you need a strong password and have a password manager, that fills in your passwords automatically, then you should use one of these 16 characters long passwords. They should be used with another authorization method or in trusted environments.
Very strong passwords for password managers and web services.
If you need a very strong password and have a password manager, that fills in your passwords automatically, then you should use one of these 32 characters long passwords. These are recommended for general application and web services.
Extremely strong passwords for password managers and database driven web services.
If you need an extremely strong password and have a password manager, that fills in your passwords automatically, then you should use one of these 64 characters long passwords. These are recommended for WordPress sites and other modern database driven web services.
About the password generator.
The password generator, that generated the passwords above, is a piece of PHP programming code, that I wrote. It loads a set of special characters, a set of numbers, a set of lower case letters and a set of upper case of letters, which it uses to create a pool of characters, that can be used one or more times to create passwords.
The pool of characters does not contain special characters, that could conflict with HTML. An example is generation of entity numbers and entity names. It then uses a random number generator to pick characters from the pool and generate passwords to the given length.
Each password, that is generated above, has been generated on the fly and printed directly to this page. None of the passwords have been through a database, have been written to temporary storage or logged in this process.
Use a password manager.
Read more about, how to use strong passwords in my post Use a password manager to store and fill in your passwords.