Click the "Check Your Password" button to check if the password you key in on a webpage has been exposed by in previous data breaches. This check is done by checking against API provided by https://haveibeenpwned.com
Your actual password is NEVER stored or sent over the Internet to the API. This is implemented using the K-Anonymity model. NO ONE will know what you have actually typed into the password field. Check out more details at https://haveibeenpwned.com/FAQs.
Credit to https://haveibeenpwned.com for providing us with an API to access a database of pwned password.
If you still don't feel safe, then DO NOT use this extension.