Password Breach Check.
Uses HaveIBeenPwned k-anonymity: only the first 5 characters of your SHA-1 hash leave your browser. The full password never does. See how many known breaches contain your password.
Understanding your results.
A rigorous breakdown of the mathematical equations, market assumptions, and step-by-step calculations powering this tool.
The tool shows two things:
- How many times your password has appeared in known data breaches
- The time range of the breaches it was found in (recent vs historical)
If your password appears in any breach, it means that password was exposed in a real-world security incident and could be used in credential-stuffing attacks. Change it immediately.
Common mistake: assuming a password is safe just because it wasn\'t found in this database. HIBP only contains passwords from known, publicly leaked breaches. A password could be compromised through phishing, keyloggers, or breaches that haven\'t been disclosed yet.
How to use this tool.
Step-by-step workflow instructions to get the most accurate calculations for your trading strategy.
Type a password you want to check. The tool hashes it in your browser with SHA-1 and searches the Have I Been Pwned password database - over 800 million real-world breached passwords. Results appear in under a second.
Your full password never leaves this device. Only the first 5 characters of the SHA-1 hash are sent to HIBP's k-anonymity API, which returns a list of matching hash suffixes. The check happens locally. Nothing is logged or transmitted beyond that partial hash prefix.
Pro tip: if a password you use appears in a breach, change it immediately on every account that uses it. Switch to a password manager with unique passwords per site. The password generator can help you create strong replacements.
Protect your accounts
Found a breach? Here's what to do next:
Create a cryptographically secure password or passphrase - client-side, nothing leaves your browser.
Generate new passwordStore your crypto keys offline with the leading hardware wallet - immune to online breaches.
Get a LedgerSecurity tool comparison.
| Tool / Service | Type | Cost | Security | KYC | Best for |
|---|---|---|---|---|---|
| Breach Checker | Browser tool + API | Free | k-anonymity, password never leaves device | None | Checking leaked passwords |
| Password Generator | Browser tool | Free | Client-side, crypto.getRandomValues | None | Creating strong replacement passwords |
| Ledger Hardware Wallet | Hardware device | €79-€199 one-time | Cold storage, secure element chip | None | Storing crypto keys offline |
| Authy | 2FA app | Free | Encrypted cloud backup | Phone number | Adding 2FA to breached accounts |
| Bitwarden | Password manager | Free / $10yr Premium | End-to-end encrypted, open source | Email (account) | Managing passwords after a breach |
Affiliate disclosure: Some links on this page are affiliate links. If you click through and make a purchase, AHCrypto may earn a commission at no additional cost to you. We only recommend services we have tested and verified.
Privacy & safety.
K-anonymity protects your password. This tool uses the same k-anonymity protocol that Firefox and 1Password use. Your full password is never sent over the network. Only the first 5 characters of a SHA-1 hash are transmitted. The API returns hundreds of possible matches, and the final check happens locally in your browser.
No logging, no storage. We do not log, store, or transmit the passwords you check. The page does not use cookies, sessions, or tracking of any kind.
Best practice: use unique passwords for every account. Never reuse passwords across services. A password manager makes this practical - we recommend Bitwarden (free) or 1Password.
Safety & alternatives.
Avoid these mistakes
- Don't ignore breach notifications. If a password you use appears in a breach, change it immediately - not just on the affected site, but on every other site where you use the same password.
- Don't rely solely on breach checking. Prevention is better than detection. Enable two-factor authentication wherever possible.
If you prefer a password manager
Password managers like Bitwarden (free) and 1Password generate, store, and auto-fill unique passwords for every site. They also include built-in breach monitoring. This removes the burden of remembering dozens of passwords and eliminates password reuse.
