Expiry date and days left
The exact date the certificate stops being valid, and how many days remain.
SSL certificate checker
See in seconds whether a website's HTTPS certificate is valid, who issued it, when it expires and whether it covers the right names. Enter a domain and we connect to it the way a browser would.
Run the free check
Free, no account needed. It opens in the ServerMonitor app.
What it checks
Issuer
The certificate authority that issued it, such as Let's Encrypt.
Covered names
Every address the certificate is valid for, so you can spot a missing www or subdomain.
Certificate chain
Whether the server sends the full chain of intermediate certificates, a common reason a site works for you but fails on some phones.
Hostname match
Whether the certificate actually matches the address you entered.
TLS version
The version of the encryption protocol the server agreed to use.
How to read the result
- A valid certificate with plenty of days left needs nothing from you, but renewal problems often appear silently, so keep an eye on the date.
- Fewer than 30 days left is the time to check that automatic renewal works. An expired certificate shows visitors a full-page warning.
- A name mismatch or an incomplete chain are configuration problems: reissue the certificate with all your names, and install the full chain file.
A check shows you today. Monitoring watches every day.
ServerMonitor runs checks like this one on a schedule, for uptime, certificates, domains and security, and alerts you by email, Telegram, Slack or webhook the moment something changes. Free for 3 sites.
Start freeQuestions
- How do I check when my SSL certificate expires?
- Run the check and enter your domain. The result shows the expiry date and the days left. You can also click the padlock in your browser and open the certificate details.
- Why does my site work for me but show a warning for other people?
- Usually the server does not send the full certificate chain. Your browser may have the missing certificate cached, and other browsers and devices do not. The chain check shows this.
- Which ports does it check?
- It connects to the standard HTTPS port, 443, the way a browser does.
- Does it check subdomains too?
- It checks the address you enter. Subdomains often use a different certificate, so check each one you use, and read the list of covered names.
- How can I be warned before a certificate expires?
- A monitor can read the certificate every day and warn you weeks ahead. ServerMonitor does this for every site you add.
Related guides
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SSL certificate expired: what it means and how to fix it
Visitors see a scary warning when your SSL certificate expires. Here is why it happens, how to fix it quickly, and how to make sure it never happens again.
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SSL certificate errors explained: what each browser warning means
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Read the article →Other free tools: Is my website hacked?, Domain expiry checker