What is This Tool?
This tool will create a cryptographically secure password for you to use. The function to produce the password takes the following options, uppercase, lowercase and special characters and generates the strong password at a range between 1 and 1024 characters.
How Secure are the Passwords Created Here?
Cryptographically secure. In that, there should be no discernible pattern in their creation. The tool uses php's random_int function to piece together an unbiased set of characters based on the ones you have selected. The variable that changes the strength of your password is the types of characters you allow and the length you set. 16 characters should be more than secure enough but you can go all the way up to 1024 to create the ultimate badass password. Though admittedly this is overkill for pretty much every application I can think of.
After all, it would take around one trillion years to brute force a truly random 16 character password at around one billion tries a second. Our a solar system will probably not even be around to see the attack finished, so the 16 character setting should be enough for you.