SSL Lookup

This free SSL lookup extracts the full certificate chain and metadata for any domain. Paste a URL to view issuer details and expiration dates without signup.

How the ssl lookup parses certificates

You type a hostname and the tool initiates a TLS handshake. It pulls the leaf certificate and walks up the chain to the root. You can view SSL certificate chain details without installing anything. This includes the subject alternative names, the public key algorithm, and the signature hash. It shows you exactly what the browser sees when it validates the connection.

Most people just check the padlock icon. That only tells you the connection is encrypted. It does not tell you if the certificate expires tomorrow or if it covers your subdomains. This tool exposes the raw data. You see the validity period down to the second. You also see the distinguished names for the issuer and the subject.

• Subject Alternative Names list for multi-domain coverage.
• Public key type and bit length, like RSA 2048 or ECDSA P-256.
• Signature algorithm, such as SHA-256 with RSA Encryption.
• Validity window with exact start and end timestamps.

When to run an online SSL lookup

You need this when a browser throws a certificate date invalid warning. The error message is vague. The lookup tells you if the server clock is wrong or if the cert actually expired. You can also use it when migrating a site. You verify the new server presents the correct chain before you cut over the DNS records.

Developers use it to debug mixed content or incomplete chain errors. Sometimes a server sends the leaf cert but forgets the intermediate. Browsers might fix it using cached intermediates, but mobile clients will fail. Running a check shows you the exact chain length. You immediately spot if an intermediate is missing from the server configuration.

• Debugging incomplete certificate chain errors on mobile clients.
• Verifying Subject Alternative Names cover all required subdomains.
• Checking if a renewed certificate is actually deployed to the server.
• Auditing third-party APIs to ensure they use modern signature algorithms.

Limits of the free SSL lookup tool

This tool only works on domains with a listening HTTPS port. If the server drops the connection on port 443, you get nothing. It also cannot check internal hostnames or private IP addresses. The tool runs from a public server. It needs to reach your target over the public internet to initiate the handshake.

You will not see client certificate requirements here. Mutual TLS setups require a client cert to even start the handshake. If the target server demands one, the lookup will just time out or fail. It also does not test the actual HTTP headers like HSTS. It strictly reads the TLS layer and the X.509 payload, ignoring what happens after the handshake completes.

How to use the ssl lookup

1. Enter the target domain name or full URL in the input field.
2. Click the lookup button to initiate the TLS handshake.
3. Review the leaf certificate details, including the expiration date.
4. Scroll down to inspect the intermediate and root certificates in the chain.
5. Check the Subject Alternative Names to verify subdomain coverage.

Common certificate signature algorithms

Here are the signature algorithms you will see in the results, ranked from legacy to modern.

Frequently asked questions

Is this SSL lookup tool completely free?

Yes, you can run as many checks as you need without paying or creating an account. There are no hidden tiers or credit limits for standard use.

Why does the tool fail to connect to my server?

The tool needs to reach your server on port 443 over the public internet. If you have a strict firewall, or if the server only listens on a non-standard port, the handshake will fail.

How do I check SSL certificate details for an internal domain?

You cannot use this online tool for private networks. You need to run a local command line utility to connect to internal IP addresses or local hostnames.

What should I do if the expiration date looks wrong?

Check the server system clock first. If the server time is incorrect, the certificate will appear invalid. If the clock is fine, you need to install the newly renewed certificate on your web server.

Does this tool check for revoked certificates?

No, it only reads the static data embedded in the certificate file. It does not perform OCSP queries or download CRL files to check if the certificate has been revoked by the issuer.