Best Free Website Security Scanners in 2026

Search for the best free website security scanner and you get listicles that mix tools doing completely different jobs: a header grader next to a penetration-testing platform next to a malware checker. They are all "scanners", but putting them in one ranking without saying what each one gives you for free is how people end up trusting a green badge that never tested what they cared about.

This list is narrower. For each tool we looked at what the free version does, whether it needs an account, and what it does not test. Trials are not free tiers, so tools that only offer a time-limited trial are listed separately at the end. We made one of the tools below (SecScanner), so we say so, apply the same criteria to it as to the rest, and do not claim it is the best at everything. Facts about third-party tools come from their own pages as of October 2026; check the current terms before relying on them.

How we ranked them

The ranking answers one question: how much does a non-specialist site owner get for free in a single sitting? We scored on four things:

• What is tested. Headers, TLS, DNS and email, application vulnerabilities, malware.
• Setup. Paste a URL, or install and configure software.
• Passive or active. Does it only read what your site publishes, or does it send attack-style requests (which needs permission and care).
• Free limits. What stays behind a paywall or an account.

A developer comfortable with Docker would rank ZAP and Nuclei first; they are the most powerful free tools here. We rank them lower only because of the setup and judgement they demand.

Quick comparison

Pentest-Tools also has a free edition, covered below. It does not fit a ranking by "paste a URL" convenience, so it sits in its own section.

1. MDN HTTP Observatory: best free check for HTTP headers

Mozilla's Observatory moved to MDN in July 2024 and is still free. It grades how well a site uses security-related HTTP headers and gives a score and letter grade. Its own FAQ says it tests for protections against cross-site scripting, manipulator-in-the-middle attacks, cross-domain information leakage and insecure cookies, among others, and that it does not test for outdated software, SQL injection or vulnerable CMS plugins. It also has no TLS or certificate analysis, since it focuses on HTTP data.

• Free: yes, and its FAQ and API examples show no account or key. A site can be re-scanned at most once every 60 seconds.
• Worth knowing: the scan history for each domain is public.
• Use it for: a fast, well-understood read on CSP, HSTS, cookie flags and friends. Pair it with a TLS tool.

2. Qualys SSL Labs: best free check for TLS

SSL Labs describes its test as a free online service that performs a deep analysis of the configuration of any SSL web server on the public internet. It is the reference for certificate chain, protocol versions and cipher suites. The test form has a checkbox to keep your result off the public boards, and Qualys states it uses submitted information only to provide the service. The page mentions no account.

• Doesn't cover: HTTP headers, DNS records, application behaviour. It is deliberately a TLS tool.
• Use it for: verifying certificate and protocol configuration after a change. See our SSL certificate check guide or the SSL checker for a lighter-weight pass.

3. SecScanner: one report across TLS, headers, DNS and content

This is our product, so read it with that in mind. SecScanner runs a passive, non-intrusive scan: it reads what your site publishes (TLS handshake, response headers, public files, DNS records) and never sends exploit payloads. Anyone can paste a URL and run a scan with no signup; scans are rate-limited per IP, and a full scan takes roughly one to three minutes.

The registry currently holds 62 checks across TLS, headers, content and DNS/email, and 24 of them are shown in the free report. The scanner runs the whole set, but the remaining checks are shown only after you pay, either with a one-time unlock of a single domain's report or with a subscription. We would rather say that plainly than call the tool "free" without qualification. Continuous monitoring with alerts is a paid feature.

• Strengths: one report covering TLS, headers, cookies, DNS and email authentication (SPF, DKIM, DMARC) instead of three tools; every finding comes with remediation text.
• Limits: not a penetration test. It will not find injection flaws or broken access control, and it only audits what is externally visible. Part of the report is paid.
• Use it for: a first full configuration pass on a site you own. For head-to-head detail against the other tools, see our comparison of Mozilla Observatory, ImmuniWeb and SSL Labs alternatives.

You can run a scan without an account.

4. ImmuniWeb Community Edition: widest range of free tests

ImmuniWeb's free page lists a set of Community Edition tests: a Website Security Test (which it describes as covering vulnerability scanning, HTTP security headers, compliance checks and Content Security Policy), an SSL Security Test for web and email servers, a Mobile App Security Test, an Email Security Test, a Website Privacy Test, a Dark Web and Threat Exposure Test and a Cybersecurity Rating. It describes the service as offered free to raise security awareness.

• Couldn't confirm: the free page does not state whether an account is required, nor daily limits or terms for commercial use. Read their terms before scanning anything beyond your own site.
• Use it for: a second opinion with a different set of tests, especially email and privacy.

5. SecurityHeaders.com: simplest headers grader

SecurityHeaders.com, created by Scott Helme in 2015, grades a site's response headers with a letter grade and links to how to fix each missing one. It has changed hands (Probely acquired it in 2023, and Snyk then acquired Probely), and the paid API was announced as discontinued in 2026, but the web scanner is described as a free tool that remains available. Its creator has called it an educational tool rather than a definitive assessment.

• Overlaps with: MDN Observatory, which tests more header-related behaviour including cookies. Running both is cheap and useful because they weigh headers differently.
• Couldn't confirm: we could not load the site directly while writing this, so details of the current scan options come from secondary sources.

6. Sucuri SiteCheck: free malware and blacklist check

SiteCheck answers a different question from the tools above: is this site visibly infected or blacklisted? Sucuri says the free scanner looks for known malware, viruses, blacklisting status, errors and out-of-date software, plus malicious links, redirects, iframes and JavaScript in the page source. It is equally explicit about limits: a remote scanner "will not detect anything on the server-side", results are not guaranteed, and malware removal, continuous monitoring and the firewall are separate Sucuri services.

• Use it for: a quick sanity check if you suspect injected spam or redirects. It is not a configuration auditor.
• Doesn't replace: a header, TLS or DNS check.

7. OWASP ZAP: best free tool for testing the application

ZAP is free and open-source software and describes itself as the world's most widely used web app scanner. It is the closest thing to a free vulnerability scanner in the sense most people mean it. Its baseline scan runs the spider against a target (one minute by default) and waits for passive scanning to finish; the docs state this "doesn't perform any actual attacks" and suits CI/CD, even against production. ZAP also offers active scanning, which does send attack-style requests. Only run those against systems you are authorised to test, ideally staging.

• Strengths: real application-layer findings, authenticated scanning, scriptable in CI, no cost.
• Limits: you install and run it, tune it and triage noise yourself. It is not a hosted one-click service.

8. Nuclei: free template-driven scanner for developers

Nuclei is an MIT-licensed command-line scanner from ProjectDiscovery. It uses YAML templates, maintained by the community in a separate repository, that describe how to send requests and recognise a vulnerable response. The open-source CLI is free; ProjectDiscovery also sells cloud-hosted Pro and Enterprise editions and has a free cloud tier with monthly limits on stored findings and template access.

• Strengths: fast checks for known CVEs, exposed panels and misconfigurations across many hosts; easy to write your own template.
• Limits: it is an active scanner. You choose the templates, so it is only as good as your choices, and it should only be pointed at assets you have permission to test.

Free editions and trials that are easy to mix up

• Pentest-Tools. Its pricing page lists a Free Edition described as "limited, but you can perform light scans": up to 5 scanned assets per monthly cycle, one workspace, 90 days of history, and most scanners marked as limited. Authenticated web-app scans, API access and exploitation tools are excluded. It is a real free tier but a constrained one; check the per-tool limits before you plan around it.
• HostedScan. The pricing page we checked lists no free plan: the lowest tier is Basic at $39 per month with a 14-day trial. It bundles Nmap, SSLyze, ZAP, OpenVAS and Nuclei, but it is a trial, not a free tier, so it is not ranked above.

We also left out MXToolbox and Hardenize. Their pricing pages did not load or did not state free-tier terms when we checked, and we would rather omit a tool than guess. If you only need email authentication, see our email security checker.

What to use when

A sensible free setup

1. Run an all-in-one scan (SecScanner or ImmuniWeb) to see the shape of the problem.
2. Fix what it flags, then re-test headers with MDN Observatory and TLS with SSL Labs, because they go deeper in their own layer.
3. If you ship code, add a ZAP baseline scan to CI, where passive scanning is safe to repeat.
4. Only run active scanners (ZAP active scan, Nuclei) against assets you own, ideally on staging.

For a checklist of what to do with the findings, see the website security audit checklist, and for a plain-language read on whether a site is safe to visit or run, see how to check if a website is safe.

Bottom line

The honest answer to "which is best" is: the one that tests the layer you are worried about. Headers: Observatory. TLS: SSL Labs. Malware: SiteCheck. Application bugs: ZAP. If you want one report across the configuration layers without installing anything, that is what we built SecScanner for, with the caveat that part of its report is paid.