SSL Certificate Checker
See who issued a site's TLS certificate, when it expires, which names it covers and whether browsers will trust it.
Este contenido está en inglés.
Ejemplos resueltos
Checking a shop certificate
shop.example.co.uk entered without https://
Issuer: a public certificate authority. Valid from: 1 November 2025. Valid until: 1 December 2026. Days remaining: 47.
This is an illustrative result; a certificate with 30 or fewer days left is worth renewing now.
Finding an expired certificate
old-blog.example.co.uk entered in the address box
Status: expired. Valid until: 3 October 2026, 12 days ago. Browsers will show a warning page to visitors.
The check reads the public HTTPS certificate, so renewing it on the server will clear the warning once the new certificate is installed.
Sobre SSL Certificate Checker
An SSL certificate checker inspects the HTTPS certificate a website presents and reports the key details in one view. You can see who issued the certificate, the expiry date, how many days remain, which names it covers and the protocol in use. It also shows whether browsers are likely to trust the certificate, which is the detail behind the padlock or the security warning visitors see.
Certificates are easy to forget because they usually renew automatically, but a failed renewal, a missing intermediate certificate or an uncovered hostname can break HTTPS for every visitor. Checking the certificate before a launch, after a server move or when expiry is approaching helps you catch problems before browsers start showing warnings.
Cómo usar SSL Certificate Checker
- Enter the domain name, such as example.com, without a path.
- Check the trust result before reading any other detail.
- Look at the expiry date and the days left.
- Confirm the names covered include every address you use, such as www.
- Renew or reinstall the certificate if the days left are low or the trust check fails.
Usos habituales
- Confirming a certificate covers every subdomain before a site goes live
- Checking how many days remain before a manual renewal is due
- Diagnosing a browser warning that says the certificate is not trusted
- Verifying the certificate after moving a site to a new server
Preguntas frecuentes
How long are SSL certificates valid for?
Public certificates have a fixed validity period, and the maximum has been shortening over time. Some certificates are issued for just 90 days, and these are normally renewed automatically well before they expire. Longer terms still exist, so rely on the expiry date in the report rather than assuming a period. Shorter lifespans limit how long a compromised key can be misused.
Do SSL certificates renew automatically?
Many certificates renew automatically through the hosting platform or the tool that issued them, usually well before expiry. Automatic renewal can still fail, for example if the domain no longer points to the server or the validation check is blocked. If the days left keep falling without a renewal, investigate the automation rather than waiting for the certificate to expire.
Why does a valid certificate show as not trusted?
A certificate can be unexpired yet still untrusted if the authority that issued it is not recognised by browsers, or if the server does not send the intermediate certificates that link it to a trusted root. Self-signed certificates also fail this check. Reinstalling the full chain supplied by the issuer usually resolves the warning.
What is the difference between SSL and TLS?
SSL is the older protocol name, and its versions are now deprecated. TLS, or Transport Layer Security, is its successor, but people still say SSL certificate for the certificates that enable TLS. The checker reports the TLS protocol version a server negotiates, which should be a current version such as TLS 1.2 or 1.3.
Why must a certificate cover my www address too?
A certificate is valid only for the names listed in it, such as example.com and www.example.com, or a wildcard that covers subdomains. If a visitor reaches the site through a name that is not covered, the browser shows a name mismatch warning. Use the names covered list to check that the bare domain and every subdomain you use are included.