Security ToolsPassword Leak Checker
Check if your password has been exposed in known data breaches using the Have I Been Pwned API. Your password is never sent — only a partial SHA-1 hash is transmitted for privacy.
🔒 Your Privacy is Protected
Only the first 5 characters of a SHA-1 hash of your password are sent to the API. Your actual password never leaves your browser.
🔍
Enter a password and click "Check Password" to check if it has been leaked.
Related Tools
About Password Leak Checker
How It Works
- Your password is hashed using SHA-1 entirely in your browser
- Only the first 5 characters (prefix) of that hash are sent to Have I Been Pwned
- The API returns all breach hashes that share that prefix (k-Anonymity model)
- Your browser compares the full hash locally — your password never leaves your device
- A match count of 0 means the password is not in any known breach database
Why Check for Leaked Passwords
- Verify that your current passwords are not in known breach databases
- Check passwords before reusing them across multiple services
- Audit old passwords you may have forgotten to change after a breach
- Educate users and employees on the risks of common or reused passwords
- Integrate breach awareness into your security review workflow
Frequently Asked Questions
Is my password sent to any server?
No. This tool uses the k-Anonymity model from the Have I Been Pwned (HIBP) API. Only the first 5 characters of a SHA-1 hash of your password are sent. The server returns all matching hash suffixes and the comparison is done entirely in your browser.
What is the Have I Been Pwned API?
Have I Been Pwned (HIBP) is a free service created by security researcher Troy Hunt. It aggregates data from hundreds of data breaches containing billions of compromised credentials and provides a privacy-preserving API to check them.
What does it mean if my password was found?
It means your exact password appears in a publicly known data breach database. This greatly increases the risk of unauthorized access to any account using that password. You should change it immediately on every site where it is used.
What does it mean if my password was NOT found?
A result of 'not found' means the password has not appeared in any of the breach databases indexed by HIBP. It does not guarantee the password is strong — you should still use a long, unique, randomly generated password.
What is a SHA-1 hash and why is only part of it sent?
SHA-1 is a cryptographic hash function that converts any input into a fixed 40-character hex string. The k-Anonymity model means only the first 5 characters (a prefix) are sent to HIBP. This is mathematically insufficient to reconstruct the original password.
How many breach records does HIBP contain?
As of 2024, Have I Been Pwned contains over 10 billion compromised credentials from hundreds of major data breaches including Adobe, LinkedIn, RockYou, and many others.
Can I check multiple passwords at once?
Currently this tool checks one password at a time to keep the interface simple and to avoid any accidental logging of sensitive inputs. For bulk checks, you can use the HIBP API directly.
Should I use this tool to check my actual passwords?
Yes, it is safe to use. The k-Anonymity implementation ensures your real password is never transmitted. However, as a general security practice, always be cautious about where you type your passwords.
What should I do after finding a leaked password?
Change the password immediately on every site where you use it. Use a password manager to generate and store unique, strong passwords. Enable two-factor authentication (2FA) wherever possible.
Does this tool store my password or search history?
No. This tool is entirely client-side for the sensitive parts. The only data leaving your browser is a 5-character hash prefix. No passwords, full hashes, or personal data are ever stored or logged.
What if the HIBP API is unavailable?
If the API is temporarily unavailable, you will see an error message. No result means the check could not be completed, not that your password is safe. Try again after a few minutes.
How is this different from checking if my email was breached?
Checking if your email was breached tells you whether accounts associated with that email appeared in a breach. Checking a password directly tells you whether that specific password string exists in breach databases, regardless of which account it was associated with.