SSL Test: Check Any Website's SSL Certificate
Run a free SSL test on any website. Enter a domain and our SSL checker connects to it on port 443 and reports the certificate's issuer, expiry date, days remaining, trust status and the names it covers, plus the TLS protocol and cipher actually negotiated. If something is wrong, the summary tells you what to fix.
Free · no sign-upWhat an SSL certificate check looks at
An SSL test (also called an SSL certificate check) confirms that a website's certificate is valid, trusted, not about to expire and issued for the right name, and that the connection uses a modern TLS version.
| Result | What it means | What you want to see |
|---|---|---|
| Days remaining | How long until the certificate expires. Browsers show a full-page warning once it does. | Auto-renewal set up, well before zero |
| Trusted | Whether browsers will accept the certificate. | Yes |
| Issuer | The certificate authority (CA) that issued it, such as Let's Encrypt or DigiCert. | A publicly trusted CA |
| Alternative names | Every hostname the certificate covers. | Your domain with and without www |
| Protocol | The TLS version negotiated with the server. | TLS 1.2 or TLS 1.3 |
| Cipher | The encryption method used for the connection. | A modern cipher, such as AES-GCM or ChaCha20-Poly1305 |
How to check an SSL certificate
- Enter the domain such as example.com. You don't need https://.
- Press Check SSL. The checker connects to the site on port 443.
- Review the results: days remaining, trust status, covered names, protocol and cipher.
- Fix and test again. Fix anything listed in the summary, then run the SSL test again.
You can also check a certificate in your browser: click the icon to the left of the address bar, open the connection details and view the certificate. An SSL certificate checker like this one is faster when you look after several sites or want to see the server's TLS settings.
Common SSL errors and how to fix them
| Problem | Likely cause | Fix |
|---|---|---|
| Expired certificate | Renewal didn't run or failed. | Renew now and turn on automatic renewal. |
| Not trusted | Usually a missing intermediate certificate, or a self-signed certificate. | Install the full certificate chain, or use a publicly trusted CA such as Let's Encrypt (free). |
| Name mismatch | The certificate doesn't cover the hostname you entered. | Reissue it to include every name, for example example.com and www.example.com. |
| Old protocol | The server still allows TLS 1.0, TLS 1.1 or SSL. | Turn these off in your server or CDN settings and keep TLS 1.2 and 1.3 on. |
SSL certificate lifetimes are getting shorter
Under rules adopted by the CA/Browser Forum, publicly trusted certificates issued from March 15, 2026 can be valid for at most 200 days. The limit drops to 100 days in March 2027 and 47 days in March 2029. Free Let's Encrypt certificates already last 90 days.
In practice this means manual renewals no longer work. Turn on automatic renewal with your host, CDN or ACME client, and use this SSL test to confirm the new certificate is live.
What this SSL checker doesn't test
This is a quick SSL test of the certificate and the connection your browser would get. It checks the standard HTTPS port (443) only. It doesn't list every cipher suite a server supports or scan for server vulnerabilities, and a valid certificate says nothing about whether a site's content is safe: phishing sites can have valid certificates too. To check a link before you open it, use the Suspicious URL Checker.
Next: check your security headers
A valid certificate encrypts traffic. Security headers tell browsers to always use it and block common attacks.
SSL/TLS Checker FAQ
What is an SSL test?
An SSL test connects to a website and checks its SSL/TLS certificate and connection: whether the certificate is trusted, when it expires, which names it covers, and which TLS version and cipher are used.
How do I check if an SSL certificate is valid?
Enter the domain in this SSL checker. A valid certificate shows as trusted, has days remaining, and lists your domain in its alternative names.
How long do SSL certificates last?
Publicly trusted certificates issued from March 15, 2026 can last at most 200 days, falling to 100 days in 2027 and 47 days in 2029. Let's Encrypt certificates last 90 days. Turn on automatic renewal.
Why does my site say the certificate is not trusted?
Most often the intermediate certificate is missing from the server configuration, or the certificate was issued for a different domain name. A self-signed or expired certificate is also not trusted.
Does this SSL checker test port 443 only?
Yes. It checks the standard HTTPS port.
Do I need to type https:// before the domain?
No. Enter just the domain name, such as example.com.
Is a valid SSL certificate enough to make a site safe?
No. It encrypts traffic and proves the site's identity, but says nothing about the site's content. Phishing sites can have valid certificates too.
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