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Free tool

SSL / Not Secure checker

Expired certificate, hostname mismatch, and mixed content on the homepage — the three reasons Chrome says Not Secure.

Primary use
When a browser shows Not Secure or a certificate warning and you need the cause in one shareable check.
Estimated time
About 1 minute
Input type
Requires a domain/URL
Use the tool All free tools

Homepage only. Expired cert, hostname mismatch, mixed content. No crawl. No malware scan.

What “Not Secure” usually means

Chrome’s Not Secure label is not one bug. This checker looks at the three homepage causes people actually panic about: an expired certificate, a hostname mismatch, and mixed content (HTTP assets on an HTTPS page).

  • Expired: the certificate’s not-after date is in the past
  • Hostname mismatch: the certificate was issued for a different name (www vs apex is the classic)
  • Mixed content: the homepage HTML still requests http:// scripts, styles, frames, or media

How this is different from other free SSL tools

SSL Labs is thorough and slow — a cryptographic grade, not an emergency explanation. Certificate-date widgets ignore mixed content. Mixed-content tools ignore expiry. This page is tiny on purpose: the padlock question, a shareable result, and a path to repair.

  • Seconds, not a multi-minute grade
  • Tells you which Not Secure cause it is, so you do not renew a cert that is not the problem
  • Homepage mixed content from one GET — no crawl of the rest of the site
  • Shareable URL for a client, registrar, or host chat

When to use it

Use this when a browser says Not Secure, NET::ERR_CERT_DATE_INVALID, a name mismatch warning, or the padlock is missing on a site that “has SSL.” If the site will not resolve at all, start with the URL checker instead.

Methodology

  • Same SSRF-safe inspect as the URL checker: public http(s) only, DNS pin, rate limit, max five redirect hops.
  • Reads leaf certificate not-before / not-after and Subject Alternative Names, then compares them to the final hostname.
  • Parses the first HTML response for http:// asset URLs. Those URLs are listed, not fetched.
  • Priority order: cannot resolve → expired → hostname mismatch → HTTP-only → mixed content → healthy.

Limitations

  • Not a full TLS configuration grade (no cipher or protocol scoring).
  • Does not crawl the site or execute JavaScript, so some mixed content will be missed.
  • Does not inspect client certificates, CAA, or CT logs.
  • Not a malware, phishing, or reputation scan.

Privacy

Submit only public homepage URLs. HTML is read on the server to list mixed-content URLs and is not returned to the browser. Do not paste private or authenticated addresses.

FAQ

Plain answers about what this tool does and does not claim.

Why does Chrome say Not Secure if the certificate is valid? +
Mixed content. An HTTPS page that still loads HTTP scripts, stylesheets, or frames is marked Not Secure even with a perfect certificate. This checker separates that case from expiry and hostname mismatch.
Does this replace SSL Labs? +
No. It does not grade protocol versions, cipher suites, or HSTS. It answers the panic question on the homepage. Use a dedicated lab if you need a cryptographic configuration review.
Will it find mixed content on every page? +
No. One GET of the URL you paste (usually the homepage). It does not crawl, and it will miss assets injected later by JavaScript.
Is this a malware or virus scan? +
No. Rescue 404 will not turn this into a payload scanner. Expired certificates and mixed content are configuration problems, not proof of a hack.
What should I do if the check says expired? +
Reissue and reinstall the certificate at the host, panel, or CDN, then confirm auto-renewal is actually running. The SSL certificate expired guide on this site walks through the safe first steps.
Do I need to log in? +
No. Paste the URL. Optional next step is Emergency Repair or Domain & Hosting Recovery if you want a technician to fix it.

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Expired certificates, name mismatch, and mixed content are repair jobs — not a malware scan. Results stay free.

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