The Best Free Website Security Scanners (2026 Comparison)

If you're looking for a free way to check your website's security, there are more options than ever. The challenge is figuring out which ones are worth your time. Some give you a meaningful assessment. Others give you a score that doesn't mean much and an upsell page.

I've tested the free tiers and free tools that are actually available right now. Here's what each one does, what it misses, and which one to use depending on what you need.

What free scanners can and can't do

Before comparing specific tools, set your expectations correctly. Free scanners are good at checking externally visible configuration: SSL certificates, security headers, DNS records, cookies, and known technology vulnerabilities. These are passive checks that don't require authentication or special access.

Free scanners generally can't do authenticated scanning (logging in and testing from inside your app), active exploitation testing (injecting payloads to confirm XSS or SQL injection), business logic testing, or comprehensive API security testing.

For most developers shipping a web app, the passive checks are where the highest-impact, lowest-effort fixes live. Missing headers and misconfigured cookies are more common than SQL injection in modern frameworks, and they're trivially easy to fix once you know about them.

Category 1: header and configuration checkers

These tools focus specifically on your HTTP response headers and server configuration. They're fast, free, and useful for a quick check.

SecurityHeaders.com by Scott Helme is the most well-known. Enter a URL and get a letter grade (A+ through F) based on which security headers are present and correctly configured. It checks CSP, HSTS, X-Content-Type-Options, X-Frame-Options, Referrer-Policy, and Permissions-Policy.

Strengths: instant results, clear grading, and a good explanation of what each header does. Weaknesses: it only checks headers. No SSL analysis, no cookie checks, no CORS testing, no secrets scanning. It's a single-purpose tool and it does that one thing well.

Mozilla Observatory checks headers and also grades your TLS configuration, including certificate chain, cipher suites, and protocol versions. It pulls data from multiple testing tools and combines them into one report.

Strengths: broader scope than SecurityHeaders.com, includes TLS testing. Weaknesses: the interface is dated, results can take a moment to load, and the grading is strict (many well-configured sites get penalised for missing optional headers).

Category 2: SSL/TLS testers

SSL Labs Server Test (ssllabs.com/ssltest) is the gold standard for SSL/TLS analysis. It provides a detailed breakdown of your certificate, protocol support, cipher suites, key exchange, and known vulnerabilities (POODLE, Heartbleed, etc.). The A-F grading is widely recognised.

Strengths: extremely thorough TLS analysis, detailed and well-explained results. Weaknesses: slow (takes 1-2 minutes), only tests SSL/TLS (no headers, cookies, or application-level checks), and the results can be overwhelming if you're not familiar with TLS terminology.

Category 3: general vulnerability scanners (free tiers)

These are SaaS products that offer a limited free tier. They scan for multiple categories of issues but restrict the number of scans, domains, or detail level on the free plan.

Hexora (hexora.uk) runs 7 scanners in under 15 seconds: SSL/TLS, security headers, CORS, cookies, DNS/email security, exposed secrets, and technology fingerprinting. The free tier gives you 3 scans per month with severity counts and one full finding per scan. Every finding includes evidence and an AI fix prompt.

Strengths: fast, covers multiple categories in one scan, AI fix prompts you can paste into coding agents, no account required for a quick scan. Weaknesses: free tier limits you to severity overview plus one expanded finding, passive scanning only (active scanning is on the roadmap).

OWASP ZAP (Zed Attack Proxy) is the most capable free scanner available. It's open-source, runs locally, and can perform both passive and active scanning including authenticated crawling, XSS testing, and SQL injection detection.

Strengths: completely free with no limits, active scanning, extensible with plugins, used by professional security testers. Weaknesses: requires installation and configuration, steep learning curve, no hosted option (you run it yourself), and results require expertise to interpret.

Category 4: DNS and email security

MXToolbox checks your MX records, SPF, DKIM, DMARC, and blacklist status. It's specifically focused on email security and deliverability.

Strengths: comprehensive email security analysis, blacklist checking, historical monitoring. Weaknesses: email-focused only, doesn't check web application security.

DMARC Analyzer tools (several exist) provide detailed DMARC reporting and help you understand who's sending email from your domain and whether your DMARC policy is working.

Category 5: technology and CVE scanners

Wappalyzer (browser extension) identifies the technologies your site uses: frameworks, CMS platforms, JavaScript libraries, CDNs, and analytics tools. It doesn't check for vulnerabilities directly, but knowing what's running on your site is the first step to checking whether any of those technologies have known CVEs.

Snyk Website Scanner checks your site's client-side JavaScript for known vulnerable libraries. It scans the scripts loaded by your page and matches them against vulnerability databases.

Strengths: specifically targets client-side dependency vulnerabilities, fast. Weaknesses: only checks JavaScript dependencies visible in the browser, not server-side dependencies.

Which one should you use?

It depends on what you need:

Quick overall check of your web app's security posture: use a multi-category scanner that checks headers, SSL, CORS, cookies, and secrets in one go. This gives you the broadest view in the least time.

Deep SSL/TLS analysis: use SSL Labs. Nothing else matches its depth for TLS configuration.

Just headers: SecurityHeaders.com is instant and clear.

Email security: MXToolbox for a quick check, DMARC Analyzer for ongoing monitoring.

Full active scanning (and you're technical): OWASP ZAP is unmatched for a free tool, but expect to spend time learning it.

Developer shipping fast who needs a quick check before deploy: a SaaS scanner with a free tier that runs in seconds. You need something fast enough that you'll actually use it every time you deploy.

The honest truth about free scanners

No free scanner replaces a professional penetration test. If your application handles financial transactions, health data, or any information where a breach would cause serious harm, invest in a manual assessment by a qualified security professional.

Free scanners are excellent for catching the configuration issues that make up the majority of real-world findings: missing headers, weak SSL, exposed secrets, cookie misconfigurations. These are the low-hanging fruit, and fixing them meaningfully improves your security posture even before you engage a professional.

The best approach is to use a free scanner continuously (after every deploy or at least weekly) and supplement with a professional assessment when your application reaches a level of maturity, traffic, or data sensitivity that justifies the cost.