What does it mean if your password or email is "breached"?
When a website is hacked, attackers often steal its database of usernames, email addresses, and passwords. Those stolen databases get traded and combined into huge lists that criminals use for credential stuffing — automatically trying your leaked password on your bank, email, and social accounts. If a password you use has appeared in any past breach, attackers already have it on a list, so any account using that password is at risk even if the breached site had nothing to do with it.
How the password check stays private
Checking a password safely is a solved problem, and this tool uses the standard approach called k-anonymity. Your browser calculates a SHA-1 hash of the password and sends only the first five characters of that hash to the lookup service. The service returns every leaked hash that starts with those five characters, and your browser finishes the match locally. Your actual password, and even its full hash, never leave your device, and nothing is logged or stored. That means it is safe to test a password here — but as a habit, change any password this tool flags rather than testing your most sensitive one.
What to do if you've been exposed
Finding out you're in a breach is only useful if you act on it. Here's exactly what to do, in order:
- Change the exposed password everywhere you used it. Reused passwords are the real danger — one leak unlocks every account sharing it.
- Switch to a password manager so every account gets a unique, random password you never have to remember. This single change neutralizes credential stuffing.
- Turn on two-factor authentication (2FA) on email, banking, and anything financial. Even a leaked password can't get in without the second factor.
- Prioritize by exposed data. If a breach exposed passwords or security questions, treat it as urgent. If it only exposed an email address, the risk is mostly more spam and phishing.
- Watch for targeted phishing. Breached data is used to make scam emails look legitimate. Be skeptical of messages referencing a service you actually use.
Is this different from Have I Been Pwned?
This checker is built on the same trusted Have I Been Pwned breach dataset, so the underlying data is identical. The difference is the experience: it runs instantly on mobile, puts the free password check first, and — unlike a bare list of breach names — tells you exactly what to do next. It's part of a small suite of free security tools from KOSEC, alongside a reverse image search and an AI image detector.