Best alternatives to LeakCheck in 2026

When a company you have an account with gets hacked, your password and email often end up dumped in a criminal database somewhere online — and you usually never find out unless you go looking. LeakCheck is a small Windows program from ASCOMP Software that checks your saved passwords and email addresses against a public breach database (the same one used by the well-known Have I Been Pwned) and tells you which of your accounts have already been exposed, so you know which passwords to change first. Technically, ASCOMP's angle is doing this check without ever sending your actual password over the network: it uses k-anonymity, the same privacy technique Have I Been Pwned's own API popularized, where only a partial hash prefix leaves your machine and the match happens locally. It's a native Windows desktop app (7 through 11, plus Server 2012-2025) that pulls in saved browser passwords, encrypts everything locally with Windows DPAPI, and gives you a dashboard overview plus (Professional edition) automatic ongoing monitoring with real-time breach alerts.