Free SSL Certificate Checker
See whether a website’s SSL certificate is valid, when it expires and how well the secure connection is configured. No account needed.
Free, with no sign-up. Fair-use limits apply. To enforce them we keep the domain you enter and a scrambled form of your IP address for 30 days, as described in our privacy policy.
Why certificate checks matter
An SSL or TLS certificate is what allows a browser to open your website over a secure connection and show the padlock. When it expires, or does not match the name being visited, browsers put a full-page warning in front of your visitors, and most of them leave. Search engines treat secure connections as the baseline, and an expired certificate can interrupt crawling and take a shop offline in the middle of the day. Certificates are cheap, but forgetting to renew one is expensive.
This free checker connects to the host you enter, reads the certificate it presents and reports on everything that matters, in plain English.
How to use the checker
Enter a host name such as example.com or www.example.com and press Check SSL. The tool connects to the server on the standard secure port, reads the certificate chain and tests which versions of the protocol the server accepts. Results take a few seconds. Note that a certificate is issued for specific names, so www.example.com and example.com should each be checked.
What you will see
- How many days remain before the certificate expires, and the exact expiry date.
- The issuer, and whether the certificate is valid and trusted.
- The names the certificate covers, and whether the host you entered is one of them.
- The certificate chain, including any intermediate certificates the server should be sending.
- The type and size of the key.
- Which TLS versions the server accepts, from the old 1.0 and 1.1 up to 1.3.
Reading the findings
Days remaining is the headline number. Thirty days or more is comfortable. Under fourteen deserves action, and under seven should be treated as urgent. If your certificates renew automatically, an approaching expiry is a sign that the renewal job has failed, which is worth investigating before the deadline rather than after it.
A name mismatch means the certificate does not cover the host you asked for, which is common when a new subdomain is pointed at a server that only has a certificate for the main domain. A missing intermediate certificate is a subtler fault: many desktop browsers quietly repair it, while phones, older devices and some crawlers do not, so the site appears fine to you and broken to others.
The protocol list matters too. TLS 1.0 and 1.1 are obsolete and should be switched off, and modern servers should offer 1.2 and 1.3. If the checker reports that the old versions are still accepted, your hosting provider or server configuration can usually change it in a few minutes.
Tips for trouble-free renewals
Automatic renewal is the goal, but automation fails silently, so keep an independent check. Make sure the renewal covers every name in use, including the www address and any subdomains, and that the web server is reloaded after a new certificate is issued, because a server that keeps the old one in memory will carry on serving it until it expires. If you use a wildcard certificate, remember it covers one level of subdomain only.
What a certificate check cannot tell you
A valid certificate proves the connection is encrypted and that the server controls the name. It does not prove the website is safe or well configured. For the settings that browsers also depend on, use the security headers checker, and for a broader view run the domain health check, which includes certificate checks alongside DNS, email and website tests.
Never be surprised by an expiry again
Checking by hand only helps when you remember to do it. An SEO Web Data account can monitor certificates continuously and alert you well before they expire, by email or webhook, and it can check up to ten host names for expiry in a single bulk run. It also puts uptime, performance and DNS monitoring next to your site audits, rank tracking and reports, with more than seventy domain tools available in the same place. Every plan starts with a free trial.
Frequently asked questions
How often should I check my SSL certificate?
Often enough that an expiry never surprises you. Automatic monitoring with alerts is far more reliable than remembering to check.
Why does my certificate work in my browser but fail elsewhere?
The usual cause is a missing intermediate certificate. Some browsers fetch it for you, while phones and crawlers often do not.
Do I need a separate certificate for www?
The certificate must cover every name visitors use. Many certificates list both the bare domain and the www address.
Does this tool store my certificate?
No. It reads the public certificate the server presents, and that is all.
More free tools
See all free domain tools, or read how the SSL and website checks work inside the dashboard.