Is it safe to paste my password here?

The tool hashes your password locally with SHA-1 and sends only the first 5 characters of that hash — this is the k-anonymity design used by security professionals. Your full password can never be reconstructed from what is sent.

Can I use Password Breach Checker on a phone or offline?

Yes. The layout adapts to phones and tablets, and because the logic ships as static client-side code, Password Breach Checker keeps working on intermittent connections once the page has loaded.

How does Password Breach Checker work without uploading my data?

Password Breach Checker runs entirely inside your browser's sandbox: the page loads once, and every operation after that executes on your own device's CPU. No input, file, or result is transmitted to any server — you can even watch the network tab stay silent while you use it.

Password Breach Checker

Q: What exactly does Password Breach Checker do?

Check if a password has been leaked Check whether a password has appeared in known data breaches using the k-anonymity API — only a short hash prefix is ever sent, so the password itself never leaves your device.

Check if a password has been leaked

Free Private No uploads

Password breach checker

Password

Only the first 5 characters of its SHA-1 hash are sent — the password itself never leaves your device (k-anonymity).

How it stays safe: your browser hashes the password with SHA-1, then sends only the first 5 hash characters to api.pwnedpasswords.com. The service returns a few hundred hash suffixes matching that prefix, and your browser compares locally — the k-anonymity protocol used by security professionals. The full hash (let alone the password) never leaves this page.

100% Private & In-Browser

Processed locally using client-side JavaScript. Your files and data never touch any server.

Instant & Unlimited

No registration, no waiting queues, and no limits on file conversions or generations.

Tool Overview & Guide

What is Password Breach Checker?

Check whether a password has appeared in known data breaches using the k-anonymity API — only a short hash prefix is ever sent, so the password itself never leaves your device.

Step-by-Step Instructions

How to use Password Breach Checker

Open Password Breach Checker in any modern web browser on your computer, tablet, or smartphone.

Type, paste, or configure your input data and parameters in the Password Breach Checker interface.

The tool processes your data in real time directly on your device using modern browser standards, DOM APIs, and network protocol specifications.

Copy your generated result to your clipboard, preview the output, or save your file with a single click.

Key Capabilities

No Account, No Email, No Watermarks — open the page and start working immediately.
100% Client-Side In-Browser Execution — your inputs, files, and generated data never touch any remote cloud server.
Developer-Friendly Output — results are formatted for direct paste into code, configs, or terminals.
Check if a password has been leaked

Common Use Cases

Full-stack developers, UI/UX engineers, DevOps teams, and technical leads who need to streamline daily development workflows and eliminate manual boilerplate tasks without installing software.
Check whether a password has appeared in known data breaches using the k-anonymity API — only a short hash prefix is ever sent, so the password itself never leaves your device.
Handling private or confidential material that should not be uploaded to third-party cloud services.
Running a quick one-off task — once loaded, most tools keep working even if the connection drops.

Clear Answers

Frequently Asked Questions

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