SSL CheckerFree SSL/TLS Certificate Checker

Free — no sign-up, no limits

Check Your SSL Certificate

Enter a domain to inspect its SSL/TLS certificate, security status, issuer, validity, and certificate chain.

Accepts example.com, https://example.com, or example.com:8443

  • Results in seconds
  • Live data from the target server
  • No domains data stored or tracked

Everything in one report

The same checks your visitors’ browsers run — laid out so you can act on them.

  • Validity & Expiry

    See exactly when a certificate was issued, when it expires, and how many days remain — with early-warning states before renewal is due.

  • Trust & Hostname Match

    Verify the certificate chains to a trusted root CA and matches the domain it is served on — the same checks browsers perform.

  • Full Certificate Chain

    Inspect every certificate from leaf to root: intermediates, issuers, serial numbers, and validity windows, exactly as sent by the server.

  • TLS Connection Details

    Check the negotiated TLS protocol version and cipher suite to confirm the connection uses modern encryption.

  • SANs & Custom Ports

    Review every subject alternative name a certificate covers, and check services on custom ports like example.com:8443.

  • Fingerprints & Serials

    Copy SHA-1, SHA-256, and SHA-512 fingerprints and serial numbers with one click for pinning, audits, and support tickets.

How it works

  1. Enter any domain

    example.com, a full https:// URL, or a host with a custom port — we normalize it all.

  2. We connect like a browser

    A live TLS handshake is made to the target server, exactly as a visitor’s browser would.

  3. Read the certificate

    Validity, trust, chain, cipher strength, and fingerprints — presented in plain language.

Is your certificate valid?

Find out in seconds — before your visitors see a warning.

Check a domain now

What Is an SSL Certificate Checker?

An SSL certificate checker is a tool that examines the SSL/TLS certificate installed on a website and verifies whether the certificate is valid and correctly configured.

When you check a domain, SSL Checker connects directly to the website’s server and analyzes information such as the certificate issuer, expiration date, hostname, certificate chain, TLS protocol, cipher, and subject alternative names (SANs).

An SSL certificate checker can help identify problems that may cause browsers to display security warnings or prevent users from establishing a trusted HTTPS connection.

What Does SSL Checker Check?

  • Certificate Validity

    Checks whether the SSL/TLS certificate is currently valid and identifies when it was issued and when it expires.

  • Hostname Match

    Verifies that the certificate is valid for the domain being checked and checks the certificate's Subject Alternative Names (SANs).

  • Certificate Chain

    Examines the certificates presented by the server, including intermediate certificates, to help identify incomplete or incorrectly configured certificate chains.

  • Certificate Issuer

    Shows which Certificate Authority (CA) issued the certificate and provides important certificate details.

  • TLS Protocol & Cipher

    Identifies the TLS protocol and cipher negotiated with the server during the connection.

  • Certificate Fingerprints

    Displays certificate fingerprints such as SHA-256, along with certificate serial information useful for verification and troubleshooting.

  • Custom HTTPS Ports

    Allows certificates to be checked on supported custom HTTPS ports such as example.com:8443.

Common SSL Certificate Problems

An HTTPS connection can fail for several reasons. SSL Checker helps you identify certificate and TLS configuration problems so you can understand what needs to be fixed.

  • Expired Certificate

    An SSL certificate has a defined validity period. When it expires, browsers may display a security warning and visitors may be prevented from accessing the website securely.

  • Hostname Mismatch

    A certificate must cover the domain being accessed. A hostname mismatch can occur when the requested domain isn't included in the certificate's SANs or supported names.

  • Incomplete Certificate Chain

    A server may have a valid certificate but fail to provide the required intermediate certificates. This can cause trust problems in some browsers and operating systems.

  • Untrusted Certificate

    A certificate may not be trusted if it was issued by an unrecognized Certificate Authority or if the certificate chain cannot be validated correctly.

  • Wrong Certificate Served

    A server can sometimes return a different certificate than expected because of incorrect virtual-host, SNI, proxy, CDN, or server configuration.

  • TLS Configuration Problems

    Outdated TLS protocols, unsupported cipher suites, or incorrect HTTPS configuration can prevent clients from establishing a secure connection.

Why Should You Check Your SSL Certificate?

Installing an SSL certificate is only part of securing a website. The certificate must also be valid, correctly issued, properly connected to the domain, and served with the required certificate chain.

Regularly checking your SSL certificate can help you detect expiration, hostname mismatches, certificate-chain problems, and TLS configuration issues before they affect your visitors.

  • Prevent HTTPS Warnings

    Identify certificate problems that could cause browsers to display security warnings.

  • Monitor Certificate Expiration

    Check when your certificate expires so you can renew it before visitors encounter an expired certificate.

  • Troubleshoot SSL Problems

    Inspect certificate and TLS information to help diagnose HTTPS configuration problems.

Frequently Asked Questions

What is an SSL certificate?

An SSL/TLS certificate allows a website to establish an encrypted HTTPS connection and provides information used to authenticate the website’s identity.

How do I check an SSL certificate?

Enter your domain into SSL Checker and select Check SSL. The tool connects to the specified server and analyzes the SSL/TLS certificate and connection details.

Can I check any website's SSL certificate?

You can check publicly accessible HTTPS servers that allow the SSL/TLS connection to be established. The server must be reachable from SSL Checker’s infrastructure.

Can I check a custom HTTPS port?

Yes. You can specify a custom port when supported, for example example.com:8443.

What does an expired SSL certificate mean?

It means the certificate is outside its defined validity period. Browsers and other clients may display security warnings when connecting to a website with an expired certificate.

What is a certificate chain?

A certificate chain is the sequence of certificates used to establish trust between the website’s certificate and a trusted root Certificate Authority.

What is a hostname mismatch?

A hostname mismatch occurs when the domain you're connecting to isn't covered by the certificate presented by the server.

Does SSL Checker store my domain?

SSL Checker does not keep a database of the domains you check — each result is generated in memory for that request. The only record is a routine server log entry (the domain and completion time) used to operate and debug the service.