About

Cybersecurity

SSL Certificate Checker

Check SSL certificate validity, expiry, issuer, and domain coverage for a website.

Features

  • Inspect certificate issuer
  • Check expiry dates
  • Review domain coverage

How to use it

  1. Enter a domain or hostname.
  2. Run the certificate check.
  3. Review the certificate details and validity status.

Example and use cases

Verify that a website certificate is valid and issued for the correct hostname before launch.

Useful for TLS troubleshooting, certificate monitoring, and secure website validation.

Web Security Tool

SSL Certificate Checker

Check SSL/TLS certificate validity, issuer, expiration, supported domains, TLS version and certificate details.

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SSL Certificate Check

Enter a domain name.

Example:example.com

Certificate Information

Results will appear here

No certificate result yet

Enter a domain and check its SSL/TLS certificate.

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What is an SSL/TLS certificate?

An SSL/TLS certificate helps establish an encrypted connection between a client and a server over HTTPS. The certificate contains information used during the TLS handshake, including the certificate subject, issuer and validity period.

Modern websites generally use TLS rather than the older SSL protocols, but the term SSL certificate remains commonly used.

SSL certificate details explained

Issuer

The certificate authority that issued the certificate.

Valid From

The beginning of the certificate's validity period.

Valid Until

The date and time after which the certificate expires.

Subject Alternative Names

The hostnames and domains covered by the certificate.

TLS Version

The TLS protocol version negotiated for the connection.

Signature Algorithm

The cryptographic algorithm used to sign the certificate.

Why SSL certificate expiration matters

Certificates have a defined validity period. When a certificate expires, browsers and other TLS clients can report certificate errors.

Monitoring certificate expiration is therefore an important operational task for websites, APIs and other internet-facing services.

Common SSL certificate problems

Expired certificate

The certificate is outside its validity period.

Hostname mismatch

The requested hostname is not covered by the certificate.

Untrusted issuer

The client does not trust the certificate authority or chain.

Incomplete chain

The server may not provide the required intermediate certificates.

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How SSL certificate checking works

1

Enter a domain

Enter the hostname of the HTTPS service you want to inspect.

2

Connect over TLS

The server-side checker establishes a TLS connection and retrieves certificate information.

3

Inspect certificate

Review validity, issuer, expiration, SANs, TLS version and other certificate details.

FAQ

SSL Certificate Checker FAQ

What is an SSL certificate checker?

An SSL certificate checker retrieves and examines certificate information from an HTTPS server.

How do I check when an SSL certificate expires?

Enter the domain in the checker to view the certificate's valid-until date and remaining validity period.

What is TLS?

TLS is the protocol used to provide encrypted communication between clients and servers.

What happens when an SSL certificate expires?

Clients may display certificate warnings or reject the connection depending on their validation behavior.

What is a certificate issuer?

The issuer is the certificate authority that signed and issued the certificate.

What are SANs?

Subject Alternative Names specify the DNS names and other identities covered by a certificate.

Does a valid certificate mean a website is completely secure?

No. Certificate validity does not guarantee that the web application itself is free from vulnerabilities.

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Frequently asked questions

Does this confirm the entire certificate chain?

It checks the primary certificate and common validation details, but a full chain verification often requires a deeper server-side certificate inspection.

Related developer tools

HTTP Headers CheckerWHOIS LookupDNS Lookup