How to Check Your Website Security for Free (5 Methods)

Paid pentests are valuable, but they happen once or twice a year. Free automated checks can run daily. The majority of web security incidents — XSS via missing CSP, session hijacking via insecure cookies, phishing via missing DMARC — are caught by automated surface-level analysis, not deep manual exploitation.

The goal of a free check is not to replace a full audit. It is to eliminate the obvious, fix the low-hanging fruit, and reduce your attack surface continuously.

Method 1: Browser DevTools

Best for: Cookie inspection, mixed content, CSP violations, network requests

Every modern browser ships a security panel that most developers never open past the Console tab. Chrome and Firefox DevTools give you direct access to:

• Cookie attributes (HttpOnly, Secure, SameSite)
• Mixed content warnings (HTTP resources loaded on HTTPS pages)
• CSP violations logged in real time
• Response headers on every request

How to use it

1. 1Open your site in Chrome
2. 2Press F12 to open DevTools
3. 3Go to the Application tab → Cookies — check every cookie for the HttpOnly, Secure, and SameSite flags
4. 4Go to the Network tab, reload the page, click any request, and open the Headers panel — check the response headers for Content-Security-Policy, Strict-Transport-Security, X-Frame-Options
5. 5Open the Console tab and look for any CSP violation errors or mixed content warnings

What it catches

• Missing HttpOnly or Secure flags on session cookies
• SameSite=None without Secure (a common mistake)
• Resources loaded over HTTP on an HTTPS page
• CSP violations from third-party scripts

Limitations

DevTools only inspects what is visible in the browser. It will not check your DNS configuration, email security records, or TLS cipher suites. It also requires you to manually navigate to every relevant page.

Verdict: Use this first, every time. It takes two minutes and requires nothing but a browser.

Method 2: SecurityHeaders.com

Best for: HTTP security header grading

SecurityHeaders.com, maintained by Scott Helme, scans the response headers of any public URL and grades them from A+ to F. It checks for:

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

How to use it

1. 1Go to securityheaders.com
2. 2Enter your domain and click Scan
3. 3Read the grade and expand each failing header for a description of what it does and how to add it

What it catches

Missing or misconfigured HTTP security headers are responsible for a large portion of web vulnerabilities. A missing X-Frame-Options header enables clickjacking. A missing Strict-Transport-Security header means users can be downgraded to HTTP on their first visit.

Limitations

SecurityHeaders.com only checks headers. It does not inspect TLS, cookies, DNS, email authentication records, or JavaScript vulnerabilities. It also only checks a single URL, so subdomains are not automatically included.

Verdict: Essential for header-specific diagnosis. Pair it with something that checks more layers.

Method 3: SSL Labs (Qualys)

Best for: Deep TLS/HTTPS analysis

Qualys SSL Labs is the industry standard for grading TLS configurations. An A+ from SSL Labs means your certificate, protocol versions, cipher suites, and HSTS preload configuration are all correct.

How to use it

1. 1Go to ssllabs.com/ssltest
2. 2Enter your domain
3. 3Wait 60–90 seconds for the full analysis
4. 4Review the grade and the detailed breakdown

What it checks

• Certificate validity and chain
• Protocol support (TLS 1.0/1.1 flagged as insecure)
• Cipher suite strength
• Forward secrecy
• HSTS configuration and preload status
• Vulnerability checks: POODLE, BEAST, Heartbleed, ROBOT, etc.

Reading the results

Common issues that cause B or lower

• TLS 1.0 or 1.1 still enabled (many older hosting configs)
• Weak cipher suites like RC4 or 3DES
• Missing or incorrectly configured HSTS header
• Certificate chain issues (missing intermediate certificate)

Limitations

SSL Labs only analyzes the TLS layer. Scan times can be slow. The tool does not check cookies, headers beyond HSTS, DNS, or application-level vulnerabilities.

Verdict: Run this once per quarter and after any certificate renewal or hosting change.

Method 4: ZeriFlow Free Scan

Best for: Comprehensive automated security scan across all layers

The three tools above each cover one layer. ZeriFlow runs 80+ checks across every security layer in a single scan — TLS, headers, cookies, DNS, email authentication (SPF/DKIM/DMARC), content security, privacy, performance, and accessibility — and returns a /100 score with prioritized findings.

No account required. Three free scans per day.

How to use it

1. 1Go to zeriflow.com/free-scan
2. 2Enter your domain and run the scan
3. 3Review your score breakdown by category
4. 4Expand any failing check for the exact fix

What it catches that the others miss

• Email security: SPF, DKIM, and DMARC records — missing email authentication is one of the most common ways a domain gets used for phishing
• Cookie audit: flags every cookie missing HttpOnly, Secure, or SameSite by name
• DNS security: checks for DNSSEC, dangling subdomains, and open redirects
• Privacy headers: flags Referrer-Policy, Permissions-Policy, and COOP issues
• Performance security: resource loading patterns that create security risk
• Security score: a single /100 number that makes it easy to track progress over time

Example scan output

A typical first scan on an unoptimized SaaS app might look like:

• TLS: 85/100 (TLS 1.0 still enabled by hosting provider)
• Security Headers: 40/100 (missing CSP, missing Permissions-Policy)
• Cookies: 55/100 (session cookie missing SameSite)
• Email Security: 30/100 (DMARC missing, SPF too permissive)
• Overall: 62/100

Each failing check links directly to the fix. For most teams, the first scan surfaces 6–10 actionable items that can be fixed in a few hours.

Limitations

The free tier scans publicly accessible URLs. The advanced scan (GitHub repo, ZIP upload) checks for hardcoded secrets and dependency CVEs and requires an account.

Verdict: The best single free tool for a complete picture. Start here, then use SSL Labs and SecurityHeaders.com for deep-dives on specific layers.

Method 5: npm audit

Best for: Node.js dependency vulnerability detection

If your site or API runs on Node.js, npm audit scans your package.json and package-lock.json against the npm advisory database and reports known CVEs in your dependencies.

How to use it

Reading the output

Each finding includes severity, the affected package, the patched version, and the dependency chain that introduced it.

What severity levels mean

Limitations

npm audit only covers your direct and transitive Node.js dependencies. It does not check your runtime configuration, headers, or deployed infrastructure. Some advisories are also low-risk in practice (a vulnerability in a CLI tool that never processes untrusted data, for example).

Equivalent tools: yarn audit for Yarn projects, pip-audit for Python, bundler-audit for Ruby.

Verdict: Run this in your CI pipeline on every push. It is one line of configuration and catches real vulnerabilities automatically.

Which Method to Use When

Building a Free Security Routine

The most effective approach combines these tools into a lightweight routine:

Before every deploy: - Run npm audit in CI (zero effort once configured) - Check DevTools on the staging URL for cookie and header regressions

Monthly: - Run a full ZeriFlow scan and compare the score to last month - Check SSL Labs if you have made any hosting or certificate changes

Quarterly: - Full review of SecurityHeaders.com grades across all subdomains - Review ZeriFlow email security findings — DMARC policy drift is common after domain changes

The Limitations of Free Tools

Free website security checks are excellent at finding configuration-level vulnerabilities. They are not a substitute for:

• Manual penetration testing (business logic flaws, authentication bypasses)
• Static application security testing (SAST) on your own source code
• Dynamic application security testing (DAST) with authenticated sessions
• Social engineering and phishing simulations

Use free tools to maintain a strong security baseline between more thorough assessments.

Ready to Run Your First Scan?

If you take one action after reading this, run a free scan on your site right now at zeriflow.com/free-scan. You will have a full security score and a prioritized fix list in under 60 seconds — no account, no credit card, no waiting.

Then open DevTools on your site and check your cookies. Between those two steps, you will have a clearer picture of your security posture than most sites on the internet.

Summary

Free website security checks give you real, actionable findings with zero budget. Use browser DevTools for immediate cookie and header inspection, SecurityHeaders.com for header grading, SSL Labs for TLS analysis, ZeriFlow for a comprehensive cross-layer scan, and npm audit for dependency vulnerabilities. Run them regularly and track your score over time — security is not a one-time task.