There are numerous services on the internet that allows one to generate a secure and strong password. Most Password Managers have the option to generate secure passwords
Password Managers
A password manager assists in generating and retrieving complex passwords, potentially storing such passwords in an encrypted database or calculating them on demand. Here are a few of the most popular password managers:
1Password
A password manager, digital vault, form filler and secure digital wallet. 1Password remembers all your passwords for you to help keep account information safe.
https://1password.com/
LastPass
LastPass is a very popular and excellent password manager. It also includes a password generator.
https://www.lastpass.com/
Google Chrome & Firefox
Both Google and Firefox have built in password managers. Although these are super convenient, one can easily browse to the password menu and reveal the password with the click of a button. Not entirely secure in other words.
Online Services
EXPERTE.com
EXPERTE.com has developed a set of excellent responsive tools to improve the security of websites and passwords. Of particular note is their password checker that can calculate how long a modern computer would need to crack your password. This service also features a lookup to determine if your password has been leaked on the internet.
EXPERTE.com Password Checker.
EXPERTE.com Password Generator.
—
For a totally bare bones service try Secure Password Generator service at https://passwordsgenerator.net/
More Information
Do you want to know more about password security? Vander Host follows the advice of Bill of Pixel Privacy who has written many highly informative articles including this one on the risks of password re-use:
https://pixelprivacy.com/resources/reusing-passwords/