A NEW Google tool protects your from hackers by sounding the alarm if someone has stolen your passwords.

Its free Password Checkup software can be loaded onto Google Chrome and lets you know if your account details have been compromised in a cyber attack or data breach.

Once installed, the Chrome extension runs in the background of your browser and checks any login details you used.

If your password or username matches a Google database of more than 4billion compromised credentials, the software will flag them.

An alert that pops up on your screen reads: "Password Checkup detected that your password for [website] is no longer safe due to a data breach. You should change your password now."

If a new data breach occurs, the tool will let you if any of your passwords were compromised the next time you login to Chrome.

It gives you any exposed accounts in a small list that you can click through to change your passwords.

All information is encrypted, and Google says it has no way of seeing your data.

"We built Password Checkup so that no one, including Google, can learn your account details," Google said.

"Password Checkup was built with privacy in mind. It never reports any identifying information about your accounts, passwords or device."