Vérificateur de Certificat SSL

Inspect the TLS certificate of any site - expiry, issuer, SANs and chain

100 % gratuit. Cet outil a besoin de notre serveur pour effectuer le travail : ce que vous soumettez y est traité puis supprimé, il n'est jamais conservé.

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À propos de cet outil

Inspect a website's TLS/SSL certificate - checking its expiry date, issuer, Subject Alternative Names (SANs), and the full certificate chain. Useful for verifying a certificate is valid and won't expire soon, or diagnosing HTTPS trust issues on your own or another site.

Flux de travail

Diagnostiquer un site web lent ou inaccessible

Travaillez de l'intérieur vers l'extérieur : l'hôte répond-il, la page est-elle lente, et le certificat est-il toujours valide.

  1. 1Pinguer l'hôteLatence, gigue et perte de paquets.Ouvrir
  2. 2Lancer un test de vitesseAudit de performance réel rendu par le navigateur.Ouvrir
  3. 3Vérifier le certificatUn certificat expiré bloque tous les visiteurs.Vous êtes ici
  4. 4Inspecter le DNSConfirmez que les enregistrements pointent où vous l'attendez.Ouvrir

Comment utiliser cet outil

  1. Enter domain/hostQuery live certificate presented by the server over HTTPS.
  2. Inspect certificate detailsReview issuer, validity period, SAN list, and signature chain.
  3. Check expiry and coverageConfirm all required hostnames are covered and not near expiration.
  4. Fix cert/deployment issuesRenew, reissue, or complete chain configuration on server/CDN.

Pourquoi l’utiliser

  • Prevents production outages caused by expired certificates.
  • Diagnoses trust errors from incomplete chain configuration.
  • Validates SAN coverage for multi-subdomain deployments.
  • Supports proactive HTTPS monitoring and incident prevention.

Usages courants

  • Checking cert health before major traffic campaigns.
  • Debugging browser “connection not private” warnings.
  • Auditing wildcard and SAN certificate deployments.
  • Validating post-renewal certificate installation success.

Conseils pour de meilleurs résultats

  • Renew certificates before expiry window gets tight.
  • Include both root and intermediate chain correctly on server.
  • Verify all public subdomains in SAN list after reissue.
  • Retest from CDN edge hostnames if proxy is involved.

Erreurs à éviter

  • Renewing certificate but not deploying updated chain.
  • Assuming wildcard cert covers every needed hostname pattern.
  • Ignoring staging cert warnings until production incident occurs.
  • Checking only apex domain while `www` remains misconfigured.

Questions fréquentes

Browsers will show visitors a security warning and typically block easy access to the site, since an expired certificate can no longer be trusted to verify the site's identity - this is why monitoring expiry dates matters, especially for production sites.

Additional domain names covered by the same certificate - for example, a certificate might cover both "example.com" and "www.example.com" as SANs, so both work correctly under HTTPS with one certificate.

It shows whether the certificate is properly linked back to a trusted root certificate authority through any intermediate certificates - a broken or incomplete chain can cause trust errors in some browsers/devices even if the certificate itself is technically valid.

Yes. Ssl Checker is free for normal use with no account required, and ToolBox does not add a watermark to your result.

Most tools in this category run in your browser so the file stays on your device. If a tool needs a temporary server job, files are handled for that job only and are not kept as a lasting archive.

No install needed. Open Ssl Checker in your browser, add your file or paste your input, then download or copy the result.

Yes on modern mobile browsers. For large files, a desktop browser is usually faster and more reliable.

Try a different quality or format setting, use a smaller input, or open a related tool (for example compress before convert). Keep a copy of the original file before replacing it.

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