How Secure Is My Password? - A tool for assessing your password strength
have i been pwned? - Check if your account has been compromised in a data breach
1Password - 1Password can create strong, unique passwords for you, remember them, and restore them, all directly in your web browser.
LeakCheck - Data breach search engine, low price starting from $10/mo, one email address for free, unlimited API, 7B+ entries
Firefox Monitor - Firefox Monitor arms you with tools to keep your personal information safe.
LeakBase - Check if your account credentials have been leaked.