Password Audit Bot

Password Audit Bot answers a narrower but genuinely useful question than the email-checking bots elsewhere in this list: not "has my email leaked," but "has this exact password of mine already turned up in a known breach." Its source, published on GitHub by a developer/team using the handle CS-Era as "secure-password-auditor-bot," documents a /check command and describes precisely how it protects whatever you type: instead of sending the full password anywhere, it hashes it locally with SHA-1 and sends only the first five characters of that hash to the Have I Been Pwned "Pwned Passwords" API — the same k-Anonymity technique the official haveibeenpwned.com site itself uses, which makes it mathematically infeasible for the API to reconstruct your actual password from what it receives.

The README explicitly documents privacy-by-design and security-by-design practices: no persistence (passwords are stated to never be saved), rate limiting against brute-force and denial-of-service abuse, input sanitization, and mandatory HTTPS for all communication. Because the code is open source, none of this has to be taken purely on faith — anyone can read exactly what the bot does with what you send it.

The tradeoffs are typical of a small personal open-source project rather than a funded security company: no named individual developer beyond a GitHub organization handle, no formal privacy policy document, and a modest GitHub star count suggesting limited real-world usage so far. Treat it as a technically well-built tool rather than an established brand, and remember that even a clean result from any password checker does not replace using a unique, strong password on every account.