Email Breach Checker CLI

Problem

During assessments and investigations you often need to check whether a list of email addresses appears in known breaches. Doing that one-by-one in a browser doesn't scale, and ad-hoc scripts rarely produce clean artifacts for the report.

Approach

Email Breach Checker is a small Python CLI that:

• Reads emails from .txt or .csv
• Queries the Have I Been Pwned API with polite rate limiting
• Writes a grouped summary CSV
• Logs failures separately so retries are easy

Usage sketch

export HIBP_API_KEY=your_api_key
email-breach-checker examples/emails.txt --output results.csv

Why it matters

Breach exposure is a common thread across phishing simulations, user education, and incident triage. Automating the lookup keeps the analyst focused on interpretation — which accounts matter, which services leaked, what remediation looks like — instead of copy-paste.