HeaderLint

HTTP security header scanner with A-F grading

HeaderLint analyzes HTTP security headers on the current browser tab and provides an A-F letter grade with per-header findings and copy-paste remediation guidance. Because it runs inside your existing browser session, HeaderLint can scan pages behind login — no credentials or proxy setup required. Headers analyzed: - Content-Security-Policy (CSP) - Strict-Transport-Security (HSTS) - Referrer-Policy - X-Content-Type-Options - Permissions-Policy - X-Frame-Options - X-XSS-Protection Each header is scored as Correct (100), Weak (50), or Missing (0). The overall score is a weighted sum across all seven headers, mapped to a letter grade (A through F). For every finding, HeaderLint shows: - A severity badge (Pass / Weak / Missing) - A plain-language explanation of the issue - A recommended header value you can copy directly into your server config - A link to MDN documentation Click "Copy JSON" to export the full analysis as structured JSON for reporting or automation. Supports light and dark mode based on your system preference.