SSL checker: test any website's certificate
Enter a domain name to check its SSL/TLS certificate. You'll see whether browsers trust it, whether it matches the name, how many days are left before it expires, who issued it, the certificate chain the server sends, which TLS versions it supports and whether HSTS is on. It also checks mail servers on ports such as 465, 587 and 993.
Free · No sign-up
How to use it
- Type the domain, such as example.com, or paste a full URL.
- Keep port 443 for websites, or choose a mail or other TLS port.
- Select Check SSL. The check usually takes a few seconds.
- Read the verdict and the checks, then copy the report or a link to share with your host or developer.
Why use this tool
Trust and name check
See if browsers trust the certificate and if it covers the exact name, including wildcards.
Expiry countdown
Days left until expiry, with warnings 30 and 14 days before.
Chain check
Find missing intermediate certificates that break apps and some browsers.
TLS versions
Shows whether TLS 1.3 and 1.2 work and whether outdated TLS 1.0 and 1.1 are still on.
HSTS and server
Shows the HSTS header, the cipher, the IP address and the web server.
Mail servers too
Check SMTP, IMAP and POP3 certificates on ports 465, 587, 993 and 995.
What an SSL checker tests
An SSL certificate proves that a website is who it says it is and lets the browser encrypt the connection. This checker connects to the server the same way a browser does and checks the certificate against the list of trusted authorities, the domain name and the dates.
SSL is the old name. Today every site uses TLS, but the certificates are still widely called SSL certificates.
Common SSL errors and fixes
| Problem | What visitors see | How to fix |
|---|---|---|
| Expired certificate | Your connection is not private | Renew it and reload the web server |
| Name mismatch | Certificate is for another site | Add the name, such as www, to the certificate |
| Incomplete chain | Works in some browsers, fails in apps | Install the full chain, not only the certificate |
| Self-signed | Not secure warning | Use a trusted authority such as Let's Encrypt |
| Old TLS versions | No warning, but weaker security | Allow only TLS 1.2 and TLS 1.3 |
Keep your certificate healthy
- Turn on automatic renewal. Let's Encrypt certificates last 90 days, and public certificates are getting shorter lifetimes.
- Cover both example.com and www.example.com.
- Always install the full chain file.
- Turn off TLS 1.0 and 1.1 and enable TLS 1.3.
- Add an HSTS header once HTTPS works everywhere on your site.
Privacy and limits
The check runs from our server, so it sees what any visitor on the internet sees. Only public domain names and common TLS ports can be checked. Results are kept for five minutes, so a fix may take a few minutes to show.
Frequently asked questions
How do I check if an SSL certificate is valid?
Enter the domain above and select Check SSL. The checker connects to the site and shows whether the certificate is trusted, matches the name and is within its dates.
How do I find when my SSL certificate expires?
Run a check. The number of days left and the exact expiry date are shown at the top of the result.
What does an incomplete certificate chain mean?
The server sends its own certificate but not the intermediate that links it to a trusted root. Desktop browsers sometimes fix this themselves, but phones, apps and APIs fail. Install the full chain file to fix it.
Why does my site work in Chrome but fail in other apps?
Usually because of an incomplete chain. Chrome can fetch the missing intermediate, while other clients can't.
Can I check a mail server certificate?
Yes. Choose port 465 or 587 for SMTP, 993 for IMAP or 995 for POP3.
Is a free SSL certificate as secure as a paid one?
The encryption is the same. Paid OV and EV certificates also confirm the organisation's identity, but browsers show the same padlock for all of them.
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