https://www.theverge.com/2018/2/23/17044106/1password-feature-password-leaked

1Password, the password managing app, has introduced a new proof-of-concept feature that alerts you when you use a compromised password. The feature integrates a new service that was released earlier this week by web security expert Troy Hunt called Pwned Passwords, which lets users check to see if a password they’re using has already been leaked onto the internet. The database has over 500 million passwords that have been compiled from previous breaches.

Starting today, anyone with a 1Password membership can use this service, which is integrated with Hunt’s database. To do so, just sign into your 1Password account, click on Open Vault, then select an item to view its details. If you’re on a Mac, press and hold Shift-Control-Option-C, or Shift+Ctrl+Alt+C if you’re using Windows, to unlock the proof-of-concept feature, then click on the “check password” button to see if your password matches up with any in Hunt’s database.