Bulk Password Breach Checker — Private & Local

Bulk Password Breach Checker allows you to audit your entire password collection against Billions of compromised credentials. While tools like 'Have I Been Pwned' are excellent, they typically require manual entry one-by-one. This utility solves that for power users by automating the process for your entire exported vault. Most importantly, it is built with a zero-trust architecture: your passwords are never uploaded. Instead, your browser hashes each password locally and uses a privacy-preserving protocol called k-anonymity to check for matches.

The tool uses the SHA-1 algorithm via the browser's WebCrypto API to hash your password. It then takes only the first 5 characters of that hash and sends them to the 'Have I Been Pwned' Range API. The API returns a list of all leaked hashes starting with those 5 characters. Your browser then checks if the full hash of your password matches any in that list. This means the server never knows your full hash, let alone your actual password.