← All website monitoring tools
Mozilla HTTP Observatory
Free HTTP security header grader — checks CSP, HSTS, X-Frame-Options, cookies.
Free tier: fully free public HTTP header audit
What it does well
- Completely free to use for any public URL, with no registration required.
- Provides clear letter grades and specific, actionable technical advice for remediation.
- Integrates results from other well-regarded third-party scanners like SSL Labs.
Where it falls short
- Only scans publicly accessible websites; cannot test internal or staging environments.
- Performs on-demand scans only; no continuous monitoring or automated alerting features.
- Focus is strictly on HTTP headers and TLS; it is not a vulnerability scanner.
Alternatives to Mozilla HTTP Observatory
Qualys SSL Labs
freeFree public TLS/SSL grading service — de-facto standard for cipher and config audit.
Snyk
freemiumDeveloper-first SCA + SAST — Git/IDE/CI integration, generous free tier, paid Team from $25/dev/mo.
Pentest-Tools.com
freemiumOnline toolkit of 25+ pentest scanners (web, network, recon) — paid plans from $93/mo with unlimited scans.
Wordfence
freemiumWordPress endpoint security plugin — most installed WP firewall, paid Premium from $119/yr per site.