SSL Lookup

Inspect the SSL certificate of any website

The padlock in your browser means the site has a valid SSL/TLS certificate: a digital file that proves the server is who it claims to be and lets the browser encrypt the connection. Certificates are issued by certificate authorities (CAs) such as Let's Encrypt, DigiCert or Sectigo, and every one of them has an expiry date.

This SSL lookup connects to the host and reads its certificate, showing the common name it was issued for, the issuing organization, the signature type, when it was issued and when it expires. You can also choose the port, which is useful for mail servers or services that run TLS on a non-standard port.

An expired or mismatched certificate triggers a full-page browser warning, which scares visitors away and hurts conversions. Checking ahead of time is far better than finding out from an angry customer.

How to use the ssl lookup

1. Enter the host name, for example example.com (no https://).
2. Keep port 443 for regular websites, or enter another port for services such as mail (for example 465 or 993).
3. Submit the lookup.
4. Check the common name matches your domain and note the expiry date.

Common uses

• Making sure your certificate renews before it expires.
• Confirming a new certificate was installed correctly after a renewal or server move.
• Checking which certificate authority a site uses.
• Diagnosing browser warnings like "Your connection is not private" or a name mismatch.
• Auditing the certificates of several domains you manage.

Tips and things to know

• Let's Encrypt certificates are valid for 90 days and are meant to renew automatically. If yours is close to expiry, check that the auto-renew job is running.
• The certificate must cover the exact name visitors use. A certificate for example.com won't cover www.example.com unless that name is included too.
• If your site sits behind Cloudflare or another CDN, the lookup shows the CDN's edge certificate, not the one on your origin server.
• After fixing SSL, check that HTTP redirects to HTTPS with the URL redirect checker, and review security headers with the HTTP headers lookup.

Frequently asked questions

What is the difference between SSL and TLS?

TLS is the modern successor to SSL. People still say "SSL certificate", but today's secure connections use TLS 1.2 or 1.3.

How do I know when my SSL certificate expires?

Run this lookup on your domain and read the expiring-on date. Your certificate authority or host may also send reminder emails.

Why does my browser say the certificate is not valid?

Common causes are an expired certificate, a certificate issued for a different host name, a missing intermediate certificate, or the device's clock being wrong.

Are free SSL certificates as secure as paid ones?

For encryption, yes. Free domain-validated certificates like Let's Encrypt use the same strong encryption. Paid certificates may add organization validation, warranties or support.

Does SSL help SEO?

Google has used HTTPS as a lightweight ranking signal since 2014, and browsers label plain HTTP pages as not secure, so HTTPS is effectively required.

Related tools

• HTTP headers lookup: Get all the HTTP headers that an URL returns for a typical GET request.
• URL redirect checker: Check for 301 & 302 redirects of a specific URL. It will check for up to 10 redirects.
• DNS Lookup: Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
• Whois Lookup: Get all possible details about a domain name.
• HTTP/2 Checker: Check whether a website is using the new HTTP/2 protocol or not.