Checking Whether Your Details Are in a Breach

Most large organisations will be breached at some point, and the data taken, names, emails, passwords, sometimes more, can circulate quietly long afterwards. The question that matters is narrow: are your own details among it, and where.

This is checked against your own identifiers, the email addresses, usernames and numbers that are yours, through licensed services that index known breaches. It is not a search of the wider stolen data, and it does not involve holding any of it.

A match is useful information, not a cause for alarm. It tells you which credentials to change, which accounts to harden, and which old passwords should never be reused, before anyone tries them.

The work is in the follow-through. A breached password matters most when it has been reused across accounts, so the response is to find where it was repeated and close those doors.