ZeriFlow vs SecurityHeaders.com — Full Security Audit vs Header Check

But here is the thing: security headers are only one piece of your website''s security posture. And SecurityHeaders.com only checks about 6 of them.

Let us break down how SecurityHeaders.com and ZeriFlow compare, so you can decide which tool (or combination of tools) you need.

What is SecurityHeaders.com?

SecurityHeaders.com is a free online tool created by security researcher Scott Helme. You enter a URL, and it checks whether your site sends key HTTP security headers.

Headers checked by SecurityHeaders.com:

1. 1Content-Security-Policy
2. 2Strict-Transport-Security (HSTS)
3. 3X-Content-Type-Options
4. 4X-Frame-Options
5. 5Referrer-Policy
6. 6Permissions-Policy

It gives you a letter grade from A+ to F based on which headers are present and how they are configured.

Pros of SecurityHeaders.com:

• Completely free
• Very fast — results in seconds
• Clean, simple interface
• Good educational resource for learning about headers
• Widely recognized in the security community

Cons of SecurityHeaders.com:

• Only checks ~6 HTTP response headers
• No TLS/SSL configuration analysis
• No cookie security checks
• No DNS security checks (DNSSEC, CAA)
• No email authentication checks (SPF, DKIM, DMARC)
• No privacy or information disclosure checks
• No performance or accessibility analysis
• No source code analysis
• No AI-powered recommendations
• No fix guidance — just tells you what is missing, not how to fix it

What is ZeriFlow?

ZeriFlow is a comprehensive website security scanner that runs 80+ checks across 12 security categories. It gives you a score out of 100 and provides detailed, actionable recommendations for every issue found.

Categories ZeriFlow checks:

1. 1Security Headers (11 checks) — CSP, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy, Permissions-Policy, COOP, CORP, COEP, X-DNS-Prefetch-Control, X-Download-Options
2. 2TLS/SSL (10 checks) — protocol versions, cipher suites, certificate validity, HSTS preload readiness, OCSP stapling
3. 3Cookies (6 checks) — Secure flag, HttpOnly, SameSite, cookie prefixes, session management
4. 4Content Security (6 checks) — CSP policy evaluation, mixed content, subresource integrity, trusted types
5. 5Information Disclosure (5 checks) — server header, X-Powered-By, directory listing, error page leakage, source maps
6. 6DNS & Network (6 checks) — DNSSEC, CAA records, IPv6, CDN detection, open ports
7. 7Email Security (8 checks) — SPF, DKIM, DMARC, MX configuration, BIMI
8. 8Privacy (8 checks) — third-party trackers, fingerprinting, privacy policy, cookie consent
9. 9Best Practices (6 checks) — robots.txt, sitemap.xml, favicon, canonical URLs
10. 10Performance (7 checks) — Core Web Vitals, compression, caching, image optimization
11. 11Accessibility (4 checks) — ARIA, contrast, semantic HTML, alt text
12. 12Source Code Analysis (advanced scan) — secrets detection, vulnerable dependencies, insecure patterns, API security, auth/session issues

Key Differences

What SecurityHeaders.com Misses

Getting an A+ on SecurityHeaders.com is a great start. But it does not mean your site is secure. Here is what an A+ on SecurityHeaders.com still misses:

TLS Configuration

Your site might have an A+ for headers but still be running TLS 1.0, using weak cipher suites, or serving an expired certificate. SecurityHeaders.com does not check any of this.

Cookie Security

Your authentication cookies might be missing the Secure flag, allowing them to be sent over unencrypted connections. They might be missing HttpOnly, exposing them to JavaScript theft. SecurityHeaders.com does not check cookies.

DNS Security

Your domain might lack DNSSEC, leaving it vulnerable to DNS spoofing. You might be missing CAA records, allowing any certificate authority to issue certificates for your domain. SecurityHeaders.com does not check DNS.

Email Authentication

If your domain sends email (even transactional emails), missing SPF, DKIM, and DMARC records mean anyone can spoof emails from your domain. This is a significant security and reputation risk. SecurityHeaders.com does not check email authentication.

Privacy and Information Disclosure

Your server might be leaking its software version, your error pages might expose stack traces, and third-party scripts might be tracking users without consent. SecurityHeaders.com does not check any of this.

Performance and Accessibility

Security is not the only thing that matters. Slow sites lose users, and inaccessible sites exclude them. ZeriFlow checks Core Web Vitals, compression, caching, and basic accessibility to give you a complete picture.

ZeriFlow Also Checks All the Headers

This is important: ZeriFlow checks every header that SecurityHeaders.com checks, plus 5 more. You do not lose anything by switching to ZeriFlow — you gain 70+ additional checks.

ZeriFlow checks these headers that SecurityHeaders.com also checks:

• Content-Security-Policy
• Strict-Transport-Security
• X-Content-Type-Options
• X-Frame-Options
• Referrer-Policy
• Permissions-Policy

Plus these additional headers:

• Cross-Origin-Opener-Policy (COOP)
• Cross-Origin-Resource-Policy (CORP)
• Cross-Origin-Embedder-Policy (COEP)
• X-DNS-Prefetch-Control
• X-Download-Options

Advanced Scan: Source Code Analysis

ZeriFlow''s advanced scan goes even further by analyzing your source code for:

• Secrets detection — API keys, database URLs, tokens hardcoded in source files
• Vulnerable dependencies — known CVEs in your npm, pip, or composer packages
• Insecure patterns — eval usage, SQL injection vectors, XSS vulnerabilities
• API security — missing authentication, exposed endpoints, rate limiting gaps
• Auth and session issues — weak token generation, insecure session handling

No other free header-checking tool offers this depth of analysis.

The Bottom Line

SecurityHeaders.com is a great free tool for a quick header sanity check. If all you need is to verify your 6 main security headers, it does the job well.

But if you want to understand your full security posture — headers, TLS, cookies, DNS, email, privacy, performance, accessibility, and source code — ZeriFlow gives you the complete picture.

Go beyond headers — scan your full security posture

Related comparisons:

• ZeriFlow vs Nessus — Which Security Scanner is Right for You?
• ZeriFlow vs SonarQube — Security Scanner vs Code Quality Tool
• ZeriFlow vs Snyk — Website Security Scanner vs Dependency Scanner
• Best Security Scanner for Vibe Coders (2026)

Explore ZeriFlow:

• Pricing
• Free Scan
• Advanced Scan

Further Reading

• RFC 6797 — HTTP Strict Transport Security (HSTS)
• OWASP Secure Headers Project

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