SSL certificate checker
An SSL (TLS) certificate is what puts the padlock in the browser and makes the connection to a website private. If it expires, is issued for the wrong name, or is not trusted, visitors see a full-page warning instead of your site.
This tool connects to the site’s secure port, reads the certificate it presents and tells you in plain words whether it is valid, who issued it and how many days are left.
How to read the results
- Status is the headline: valid, expiring soon, expired, wrong name, or not trusted.
- Days left counts down to the expiry date. Renew a certificate well before it reaches zero.
- Names covered lists every domain the certificate is valid for. The address you visit must be on the list.
- Issuer is the authority that signed it, such as Let’s Encrypt or DigiCert.
- Chain shows the intermediate certificates that link the site’s certificate to a trusted root.
Questions
My certificate is valid but browsers still warn. Why?
The most common cause is a missing intermediate certificate in the chain, or the name in the certificate not matching the address. Check the names covered and the chain shown here.
How often should I check?
Most free certificates last 90 days and renew automatically, but renewals can fail silently. Adding the site to the monitor lets us watch it for you.
Does this test the whole site?
It tests the certificate presented for the address you enter. Other subdomains can have their own certificates.
Related guides
More free tools
- DNS lookup
- HTTP header checker
- Redirect checker
- WHOIS and domain expiry
- MX record lookup
- Robots.txt checker
- Security headers checker
Results are a snapshot taken from our servers at the moment you ask, and can differ from what you see elsewhere. siteupdown.com tests public websites only. Spotted a problem?