What is an SSL certificate?

An SSL (Secure Sockets Layer) certificate is a digital certificate that authenticates a website's identity and encrypts data transmitted between the server and browsers using TLS. It enables the HTTPS padlock in browsers.

How do I know if my SSL certificate is valid?

Enter your domain in this SSL Lookup tool. It will connect to your server and check if the certificate is currently valid, not expired, and properly configured.

What happens when an SSL certificate expires?

When an SSL certificate expires, browsers display a security warning (NET::ERR_CERT_DATE_INVALID) blocking visitors from accessing your site. Search engines may also flag your site as insecure.

What is the difference between port 443 and 8443?

Port 443 is the standard HTTPS port used by virtually all websites. Port 8443 is an alternative HTTPS port often used for development servers, admin panels, or applications that cannot use port 443.

What does SHA-256 with RSA mean in SSL?

SHA-256 with RSA is the most common SSL signature algorithm. SHA-256 is the hashing function that creates the certificate fingerprint, and RSA is the public-key encryption algorithm used to sign it.

Is this SSL lookup tool free?

Yes, the SSL Lookup tool on uptimelock.com is completely free, instant and requires no account.

Web tools

SSL Lookup

Get all possible details about an SSL certificate.

Validity Issuer Expiry Date Common Name Signature Organization

What is SSL Lookup?

The SSL Lookup tool inspects the SSL/TLS certificate of a domain by connecting directly to the server on the specified port (443 by default). It returns validity status, issuer, dates, common name and signature type.

Certificate Information

Validity status

Indicates whether the certificate is currently valid and not expired.

Issue date

Date the certificate was issued by the certificate authority.

Expiry date

Date when the certificate will expire and must be renewed.

Issuing organization

Name of the Certificate Authority (CA) that signed the certificate.

Signature type

Cryptographic algorithm used (e.g. SHA-256 with RSA).

When to renew?

>60 days

Certificate is healthy. No immediate action required.

14 - 60 days

Plan renewal soon to avoid any service interruption.

<14 days or expired

Urgent renewal needed! Browsers will display a security warning.

How to use this tool?

1Enter the hostname (e.g. example.com) without https://
2Verify the port is correct (443 for standard HTTPS)
3Review the certificate details: validity, issuer and dates

Common Use Cases

Verify your SSL certificate is valid and browser-trusted
Monitor expiry date to avoid service interruptions
Confirm the correct certificate is in place after a renewal
Diagnose SSL errors reported by a browser or monitoring tool
Inspect SSL certificates on non-standard ports (8443, 8080...)

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