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Check domain certificate status. Free online tool, no login, no sign-up.

LocalPersonal data security

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Usage Guide & Tech FAQ

Usage Guide

  1. Enter a domain or address.
  2. Click to detect expiry and certificate chain information.
  3. Use the result to plan renewal or configuration checks.
  4. Share key findings for team troubleshooting.
  5. Verify the issuer matches procurement records to catch wrong cert deployments.
  6. For many hostnames, confirm SAN covers every name users hit to avoid name mismatch errors.
  7. With CDNs, edge certificates may differ from origin certificates—investigate both paths.
  8. Intermittent failures may involve HSTS/OCSP—cross-check with openssl and external monitors.
  9. Private CAs require trust store installation; browsers may still show untrusted without roots.
  10. Record the first-seen timestamp to correlate with rotation windows or config releases.
  11. Read the title and description first to confirm this utility matches your task (avoid using the wrong tool and misinterpreting output).
  12. Paste or type input in the editor; if a sample/template is provided, load it first to learn the expected output shape.

Related Tech Knowledge

  • Expiration time comes from the certificate NotAfter field.
  • Chain information helps determine trust path and intermediates.
  • Detection relies on the network TLS handshake result.
  • If blocked or the chain is incomplete, it may fail.
  • TLS version/cipher negotiation differs by client; old clients may fail TLS1.3-only servers.
  • CT logs, CRL, and OCSP stapling affect how browsers validate chains.
  • Corporate SSL inspection replaces chains—you may be seeing the proxy, not the origin.
  • IPv6 vs IPv4 targets can change which cert/SAN applies.
  • Browser/fetch probes may differ slightly from `openssl s_client` on extensions.
  • Avoid typing sensitive internal admin hostnames on untrusted devices.
  • Core parsing and computation run in your browser; by default your raw business payload is not persisted to this site’s servers (see on-page privacy notes).
  • The pipeline is typically: read input → parse (lexical/syntactic/structured) → transform → render; failures aim to be diagnosable.