SSL Certificate Checker

Check any website's SSL certificate: issuer, expiry date, covered domains, TLS version, and whether browsers will trust it.

Check an SSL Certificate

See the certificate a website actually presents: issuer, expiry date, covered domains, and TLS version.

About SSL Checker

The SSL Checker connects to a website on port 443 and reads the certificate it presents, then reports whether it is trusted, who issued it, when it starts and expires, how many days remain, the names it covers and the chain of authorities behind it. The certificate is read from the server over a real TLS connection each time you press the button.

Use it to confirm that a certificate was installed correctly after you renew it, to catch an approaching expiry before visitors see browser warnings, or to see which names a certificate covers.

How to use the SSL Checker

Enter a domain name such as example.com (no need to add https://).
Click Check SSL. The server connects to the domain and reads its certificate.
Review the status banner: valid and trusted, expiring soon (14 days or less), not trusted, name mismatch, or expired.
Check the issuer, validity dates, days remaining, TLS version, cipher, key size, serial number, covered domain names and chain.
Use the download button to save the report as JSON.

What it can do

Real certificate lookup

A real TLS connection is made to the domain, so the result reflects the certificate the server presents. Results can be cached for up to five minutes.

Expiry countdown

See the exact validity period and days left, with a warning when expiry is near.

Trust and name checks

Reports whether the certificate chains to a trusted authority, whether it matches the domain name you entered, and the error code if not.

Names and chain

Lists the subject alternative names the certificate covers and the issuing chain.

When it is useful

Checking that a new or renewed certificate is installed correctly.
Monitoring expiry dates for your own and your clients’ sites.
Finding out which domains a certificate covers.
Diagnosing browser warnings such as "Your connection is not private".

Good to know

The tool reads the certificate presented on port 443 for the domain you enter. It does not test for vulnerabilities and is not a full security audit.
Only public domain names can be checked. IP addresses, localhost and single-word internal hostnames are rejected.
If a site presents different certificates by region or through a CDN, the result reflects what is served to our server.
A valid certificate shows the connection is encrypted; it does not prove the website itself is trustworthy.

Frequently Asked Questions

Q.Is the result live or cached?

Each check opens a TLS connection to the domain and reads the certificate it presents. Identical requests may be served from a cache for up to five minutes, so wait a few minutes after renewing a certificate before re-checking.

Q.What does "not trusted" mean?

The certificate failed validation, for example it is self-signed, expired, issued for a different name, or the chain is incomplete. The error reason is shown.

Q.How early should I renew a certificate?

Many people renew 2 to 4 weeks before expiry. The tool highlights certificates with 14 days or fewer remaining.

Q.Does it scan for vulnerabilities such as Heartbleed?

No. It only reads the certificate and basic connection details. It is not a vulnerability scanner.

Q.Can I check a site on a port other than 443?

No, only the standard HTTPS port 443 is checked.

Q.Why can’t I check localhost, an IP address or an internal server?

To prevent misuse, only public domain names such as example.com are accepted.

Q.What are subject alternative names?

They are the list of domain names a single certificate is valid for, for example example.com and www.example.com.

Q.Do you store the domains I check?

The result is returned to you and not saved as part of the tool.

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